Zr基块体非晶合金的摩擦磨损行为(英文)
《2024年Zr50Cu50非晶合金变形行为的分子动力学模拟》范文
《Zr50Cu50非晶合金变形行为的分子动力学模拟》篇一一、引言非晶合金作为一种具有独特物理、化学和机械性能的材料，在各个领域都受到了广泛的关注。
其中，Zr50Cu50非晶合金以其出色的强度、耐腐蚀性和软磁性能等特性，在众多应用中脱颖而出。
然而，对于其变形行为的理解仍需深入。
本文将通过分子动力学模拟的方法，对Zr50Cu50非晶合金的变形行为进行深入研究，以期为非晶合金的力学性能提供更深入的理解。
二、模型与方法2.1 模型构建Zr50Cu50非晶合金模型通过分子动力学模拟软件构建，其中Zr和Cu原子随机分布在模拟空间中，形成无序的结构。
模型的构建基于非晶合金的原子结构和相互作用力场。
2.2 分子动力学方法分子动力学模拟是一种基于经典力学原理的计算机模拟方法，可以模拟原子在时间尺度上的运动和相互作用。
在本次模拟中，我们采用了Lennard-Jones势能函数来描述原子间的相互作用力。
2.3 变形过程模拟通过施加外部应力，模拟非晶合金的拉伸、压缩等变形过程。
在变形过程中，记录原子的运动轨迹和相互作用力，以分析非晶合金的变形行为。
三、结果与讨论3.1 变形过程中的原子运动在拉伸和压缩过程中，Zr50Cu50非晶合金的原子运动表现出明显的无序性。
在变形初期，原子间的相互作用力逐渐增大，导致原子运动加剧。
随着变形的进行，原子间的相互作用力达到一定程度后，部分区域出现局部塑性流动。
3.2 应力-应变关系在拉伸和压缩过程中，Zr50Cu50非晶合金表现出典型的非晶态材料的应力-应变关系。
在初始阶段，应力随应变线性增加，表现出弹性行为。
随着变形的进行，应力逐渐达到峰值后出现软化现象，表明非晶合金开始发生塑性变形。
3.3 变形机制分析Zr50Cu50非晶合金的变形机制主要包括位错运动和剪切带形成。
在变形过程中，位错在原子间相互作用力的驱动下运动，导致材料的塑性变形。
同时，剪切带的形成也是非晶合金变形的重要机制之一。
无钎焊料与Zr基块状非晶合金的润湿行为
摘
要 ：通过座 滴法 研究 了 ｓ ｎ—Ｉ ｎ 、 ｓ ｎ—Ｂ ｉ 和Ｓ ｎ—Ａ ｇ—Ｃ ｕ三种焊 料分 别 与块状 非 晶合金 Ｚ ｒ Ｃ ｔ ｕ ｏ
Ａ１ 。 Ａｇ 的润湿行 为． 结 果显示在三种焊料中 ， ｓ ｎ— Ｉ ｎ对块状非 晶合金 Ｚ ｒ “ Ｃ ｕ ４ ｏ Ａｈ Ａ ｇ ｓ 的润湿性最好 ， 而Ｓ ｎ—
Ｂ ｉ 焊料对块状非 晶合 金 Ｚ ｒ ４ Ｃ ｔ ｕ 。 Ａ１ ｓ Ａｇ 的润湿 性最差． 利用 扫描 电镜 研究 了 ｓ ｎ—Ｉ ｎ焊料 与块状非 晶合金 Ｚ ｒ Ｃ ｕ 。 Ａ１ Ａｇ 的界面特征 ， 其界面处有化合物 出现．
关 键 词 ：Ｚ ｒ 基 非 晶合 金 ；无 钎 焊 料 ；润 湿 ； 界 面 文 献 标 识 码 ：Ａ 中 图 分 类 号 ：Ｔ Ｇ １ ４ ６ ；Ｔ Ｇ ４ ９ Ｉ
很重 要 的 问题 ［ １ ｌ － ｔ ２ ］ ． 例 如 使 用 电 子 束 焊 和 激 光 焊， 在连 接过 程 中控 制 加 热 温 度 和冷 却 速 率 是 非 常重 要 的． 研 究 者们 使 用 各 种 方 法来 连 接 块 状 非
了形成能力好 的 Ｚ ｒ Ｃ ｕ 。 Ａ１ Ａｇ ｓ 块状非 晶合金．
大 的应用 前景 ， 美 国报 道 了 Ｚ ｒ 基 非 晶合 金在 军工
方面 的应用 崭露 头角 Ｅ ｌ ４ ］ ， 因此块 体 非 晶合 金选 择
立合适的连接块状非晶合金 与块状非晶合金 、 块 状非 晶合 金与 晶体 合金 的方 法 是 非 常 重要 的． 但 是， 在连 接过 程 中高 温 区的 玻璃 相 重 新 形 成 是个
在这 种涉 及液 相 的连 接 过 程 中 ， 液 相 和 固相 之 间
的润 湿性 及界 面相互 作用 决定 了材料 的结合 处 的 相容 性 ， 从 而在 很 大 程度 上 决 定 了其 连 接 的 可能 性 和使用 性 能． 本 文 研究 了无 铅 焊料 与 Ｚ ｒ Ｃ ｕ 。
Zr基块体非晶合金的制备及力学性能研究的开题报告
Zr基块体非晶合金的制备及力学性能研究的开题报
告
一、研究背景
随着现代工业的发展，材料科学和工程技术的需求变得越来越高。
块体非晶合金是近年来发展最快的新型材料之一，具有优异的力学性能、良好的抗腐蚀性和高温稳定性等特点，广泛应用于航空航天、电力设备、汽车制造、医疗器械等领域。
二、研究目的
本研究旨在探究一种新型Zr基块体非晶合金的制备方法及其力学性能，为推广和应用块体非晶合金提供科学依据。
具体研究目的如下：
1. 确定Zr基块体非晶合金的制备工艺及优化条件
2. 分析Zr基块体非晶合金的组织结构、相变情况和热稳定性
3. 测定Zr基块体非晶合金的力学性能，如硬度、强度、韧性等指标
4. 探究Zr基块体非晶合金的抗腐蚀性能及其在实际应用中的可行性。
三、研究内容
1. 块体非晶合金的制备：采用真空熔炼-铸造法制备Zr基块体非晶
合金，确定制备温度、熔炼时间和铸造条件，得到均匀的块状非晶态合
金样品。
2. 组织结构和相变分析：采用X射线衍射仪和差热分析仪等测试手段，分析样品的相组成、晶化温度和热稳定性。
3. 力学性能测试：测定样品的硬度、强度、延伸率和断裂韧性等力
学指标，分析材料的力学性能及其和组织结构的关系。
4. 抗腐蚀性能测试：利用电化学方法和盐雾实验等测试手段，研究Zr基块体非晶合金的耐腐蚀性和在不同环境下的耐久性。
四、研究意义
本研究不仅能够为Zr基块体非晶合金材料的开发和应用提供理论依据，同时还可以为材料科学和工程技术领域的进一步研究提供新思路和方法，推动块体非晶合金材料的发展和应用。
《2024年Zr50Cu50非晶合金变形行为的分子动力学模拟》范文
《Zr50Cu50非晶合金变形行为的分子动力学模拟》篇一一、引言非晶合金作为一种具有独特结构和性能的材料，在工程领域具有广泛的应用前景。
Zr50Cu50非晶合金作为其中的一种典型代表，其变形行为的研究对于理解非晶合金的力学性能和优化其应用具有重要意义。
本文采用分子动力学模拟方法，对Zr50Cu50非晶合金的变形行为进行深入研究，以期为非晶合金的力学性能研究和应用提供理论依据。
二、模型与方法2.1 模型构建Zr50Cu50非晶合金模型通过分子动力学模拟软件构建，采用随机网络模型来模拟非晶态结构的特点。
模型中，Zr和Cu原子以50:50的比例随机分布，以反映实际合金的成分。
2.2 分子动力学模拟方法分子动力学模拟采用经典牛顿力学原理，通过求解原子的运动方程来模拟材料的变形过程。
在模拟过程中，我们采用了合适的势函数来描述原子间的相互作用力。
三、模拟结果与分析3.1 变形过程中的结构变化在模拟过程中，我们观察了Zr50Cu50非晶合金在变形过程中的结构变化。
发现随着应力的增加，原子间的距离逐渐变化，非晶态结构的无序性逐渐减弱。
在一定的应力作用下，合金出现了一定程度的剪切带现象，但与晶态材料相比，其剪切带发展速度较慢，显示出较强的韧性。
3.2 原子运动与变形机制通过对原子运动轨迹的分析，我们发现Zr50Cu50非晶合金的变形机制主要是通过原子间的相对位移来实现的。
在变形过程中，部分原子发生滑移和重排，使得合金在保持较高强度的同时展现出良好的塑性。
此外，我们还观察到了一定程度的局部原子重新排列现象，这种结构重排有利于缓解局部应力集中，从而提高合金的抗疲劳性能。
3.3 力学性能分析通过分子动力学模拟得到Zr50Cu50非晶合金的应力-应变曲线。
结果表明，该合金具有较高的屈服强度和良好的塑性。
此外，我们还发现该合金在变形过程中表现出较好的能量吸收能力，这为其在冲击载荷等复杂环境下的应用提供了有利条件。
四、讨论与展望通过对Zr50Cu50非晶合金的分子动力学模拟，我们深入了解了其变形行为和力学性能。
Zr基大块非晶合金的摩擦磨损性能_陈伟荣 (1)
第23卷 第1期摩擦学学报V o l23, N o1 2003年1月TR I BOLO GY Jan,2003 Zr基大块非晶合金的摩擦磨损性能陈伟荣1,2,王英敏2,羌建兵2,徐卫平2,王德和2,董 闯2,徐 洮3,张爱民3(1.大连大学机械工程系,辽宁大连 116622;2.大连理工大学三束材料改性国家重点实验室,辽宁大连 116024;3.中国科学院兰州化学物理研究所固体润滑国家重点实验室,甘肃兰州 730000)摘要:研究了以等电子浓度和等原子尺寸为依据设计的6种不同成分的非晶合金以及同非晶合金成分相同的4种晶态合金在干摩擦条件下同GC r15钢对摩时的摩擦磨损行为.结果表明:6种不同成分非晶合金的摩擦系数相近,均在0.5～0.6范围以内;4种晶态合金的摩擦系数均在0.4～0.5范围内,相同成分的晶态合金的摩擦系数比非晶合金的低,且显微硬度和耐磨性较高;非晶合金的磨损机制主要为塑性流变,晶态合金的磨损机制主要为脆性断裂以及磨粒磨损.关键词:Zr基合金;大块非晶;显微硬度;摩擦磨损性能中图分类号:T G139+.8文献标识码:A文章编号:100420595(2003)0120014204 近几十年来,非晶合金以其独特的结构特征和良好的机械、物理及化学性能而受到人们的关注.尤其是20世纪90年代初以来,人们成功地制备出Zr 基[1]、M g基[2]等合金系大块非晶,并在大块非晶合金形成机制、非晶制备方法以及性能研究等方面取得了进展.在针对能够形成大块非晶的合金系的研究中, Zr2A l2N i2Cu合金系一直是研究的焦点,这是因为该合金体系既不含贵金属,也不含有毒元素,且具有优良的机械、物理和化学性能.有关非晶合金的摩擦磨损性能已有研究[3,4],大多集中于薄带、薄片和薄板等形状的非晶合金,而针对大块非晶的摩擦磨损性能的研究较少.本文就非晶合金的成分设计独辟蹊径,从合金电子结构和原子尺寸的角度,以等电子浓度和等原子尺寸为判据,设计了6种不同成分的合金[5],研究其在干摩擦条件下的摩擦磨损性能,并与成分相同的晶态合金进行对比分析.1 实验部分1.1 材料的制备试验以99.9%Zr、99.999%A l、99.99%N i和99.99%Cu(质量分数计)为原料,采用电弧熔炼法,在氩气保护气氛中经3次反复熔炼,得到成分均匀的试验所用6种非晶合金的高纯母合金,将其用自制的吸铸设备在高真空下制得直径3mm、长度30mm的合金棒.同样用电弧熔炼法制备与1号、2号、4号和5号合金成分相对应的4种晶态合金的母合金,用吸铸法制备成直径为6.5mm的合金棒.非晶及相应成分的晶态合金的结构由岛津X射线衍射仪(XRD)测定(Cu靶,KΑ辐射).1.2 试验方法采用球2盘往复运动形式,在SRV摩擦磨损试验机上进行摩擦磨损试验.上试样为<10mm的GC r15钢球,硬度为55H R C;从所制备的10种不同成分的非晶及晶态合金试棒截取,并用502胶粘接到直径为22mm的纯A l圆盘上,圆盘经减薄后,使总厚度达到试验机所要求的标准厚度7.88mm.试验条件为:干摩擦,温度20℃,相对湿度28%,法向载荷20N (施加于上试样),振幅1mm,频率25H z,试验时间20m in.摩擦系数由试验机自动纪录.利用JS M2 5600LV型低真空扫描电子显微镜(SE M)测量磨痕形貌和尺寸,由此计算出磨损体积损失[6].用DM H2 2L S型显微硬度计测量样品的努氏硬度H K,所加载荷为0.098N,加载时间15s.2 结果与分析2.1 非晶及晶态合金结构试验中所用的10种试样的成分与结构见表1.可见,6种非晶合金成分满足等电子浓度和等原子尺收稿日期:2002203214;修回日期:2002206227 联系人陈伟荣,e2m ail:rem iliu@m ail.dlp .作者简介:陈伟荣,女,1963年生,博士,副教授,目前主要从事大块非晶合金研究.表1 所制备的10种合金试样的成分和结构Table1 Co m position and structure of the sam ples A lloy N po siti on Structure1#Zr65.5A l5.6N i6.5Cu22.4Amo rphous2#Zr65.3A l6.5N i8.2Cu20Amo rphous3#Zr65A l7.5N i10Cu17.5Amo rphous4#Zr64.8A l8.3N i11.4Cu15.5Amo rphous5#Zr64.5A l9.2N i13.2Cu13.1Amo rphous6#Zr63.8A l11.4N i17.2Cu7.6Amo rphous7#Zr65.5A l5.6N i6.5Cu22.4C rystalline8#Zr65.3A l6.5N i8.2Cu20C rystalline9#Zr64.8A l8.3N i11.4Cu15.5C rystalline10#Zr64.5A l9.2N i13.2Cu13.1C rystalline寸规律,具有相同的电子浓度e a和平均原子尺寸R a.其特征为:从1#至6#合金,Zr含量变化很小,A l 和N i含量增大,Cu含量减小.从1#至6#合金的XRD图谱仅存在1个宽峰,而无明显的晶体相的衍射峰[5],这说明6种合金主要以非晶相形式存在.7#合金和8#合金的组分与1#合金和2#合金的相同,其XRD图谱呈现晶态特征,其组成相主要为体心四方(t I)Zr2Cu结构相;9#合金和10#合金的组分与4#合金和5#合金的相同,其XRD图谱显示多相组成特征,主要为体心四方Zr2Cu结构相、简单正交(oP)结构相、简单六角(hP)结构相及其它未知相.2.2 硬度及摩擦磨损特性图1分别示出了6种非晶合金和4种晶态合金试样同GC r15钢对摩时的摩擦系数随时间变化的关系曲线.可以看出:非晶合金的摩擦系数随时间的变化而出现一定波动,大致在0.5～0.6范围以内变化[图1(a)];而4种晶态合金的摩擦系数值在0.4～0.5范围内变化[图1(b)],比非晶合金的摩擦系数略低.另外,晶态合金在试验起始阶段的摩擦系数较低,大约经过2～4m in进入稳定状态,此后其波动较小;而非晶合金在试验起始阶段的摩擦系数即保持稳定,但出现一定的波动.表2示出了10种试样的硬度、摩擦系数及磨损体积损失数据.可见:6种非晶合金的硬度差别不大,4种晶态合金的硬度亦相近;但4种晶态合金的硬度比同样成分的非晶合金的高;6种非晶合金的摩擦系数差别不大,4种晶态合金的摩擦系数也很接近;但4种非晶合金的摩擦系数比相同组成的晶态合金的高,且非晶合金的磨损体积损失较大.相同成分的非晶合金与晶态合金相比,其硬度、摩擦系数和耐磨性均存在差别,晶态合金的摩擦系数较低,而硬度和耐磨性较高.这主要归因于其不同的结构特征.换言之,晶态合金由多相化合物组成,硬质化合物相对硬度和耐磨性的提高起着非常重要的作用;而非晶合金具有结构和化学均匀性,同多相结构相比,这样的均匀相结构具有更低的硬度和更高的塑 (a)Six amo rphous alloys(b)four crystalline alloysF ig1 F ricti on coefficientΛas a functi on of testingti m e t fo r ten samp les图1 不同合金试样在干摩擦条件下同GC r15钢对摩时的摩擦系数随试验时间的变化关系性和韧性,从而导致摩擦系数因塑性变形的加剧而增大.6种不同成分的非晶合金的磨痕形貌特征类似,图2给出了其中2个试样的磨痕形貌SE M照片.由图2(a)可见,非晶合金在磨损过程中产生了严重的塑性变形,其主要磨损机制为塑性流变;从图2(b)可以观察到非晶合金磨损后的疏松组织,表明非晶合金具有非常好的塑性和韧性.图3示出了2种晶态合金的磨痕形貌SE M照片,可见明显的裂纹、剥落的碎片状磨屑[图3(a)]以及压碎的磨粒[图3(b)].与此同时,从图3(a)还可以观察到明显的犁沟迹象,表明晶态合金的磨损机制主要为脆性断裂和磨粒磨损.因此,本试验中的Zr基非晶合金的磨损机制不同于成分相同的晶态合金的磨损机制.一般认为,在干摩擦下的摩51第1期陈伟荣等: Zr基大块非晶合金的摩擦磨损性能表2 所制备的10种试样的硬度、摩擦系数和磨损体积损失Table 2 Hardness ,averaged fr iction coeff ic ien t ,and wear volu m e loss of var ious sam plesA lloy N o .Compo siti on H ardness H K M PaA veraged fricti oncoefficientW ear vo lum e lo ss mm 31#Zr 65.5A l 5.6N i 6.5Cu 22.435.00.5140.2952#Zr 65.3A l 6.5N i 8.2Cu 2035.10.5770.3253#Zr 65A l 7.5N i 10Cu 17.534.20.5670.2744#Zr 64.8A l 8.3N i 11.4Cu 15.535.90.5820.2975#Zr 64.5A l 9.2N i 13.2Cu 13.134.40.5520.2746#Zr 63.8A l 11.4N i 17.2Cu 7.638.50.5120.2757#Zr 65.5A l5.6N i6.5Cu 22.449.10.4120.2628#Zr 65.3A l 6.5N i 8.2Cu2048.10.4080.2699#Zr 64.8A l 8.3N i 11.4Cu 15.547.40.4680.24710#Zr 64.5A l 9.2N i 13.2Cu 13.148.20.4740.245(a )6#alloy (b )2#alloyF ig 2 SE M m icrograph s of w o rn surfaces of amo rphous alloys图2 非晶合金磨痕形貌SE M 照片(a )9#alloy (b )7#alloyF ig 3 SE M m icrograph s of w o rn surfaces of crystalline alloys图3 晶态合金磨痕形貌SE M 照片擦磨损试验过程中,摩擦副接触表面局部闪温可达约1000℃,远远超出了非晶合金的晶化温度.在所制备的6种非晶合金中,6#合金的晶化温度最高,为758K [5].应该指出的是,即使闪温很高,也并不一定导致合金晶化;但这种局部瞬时高温对合金结构和性能的影响不容忽视.实际上,在较高的闪温下合金可处于过冷液相区温度范围内[6],而在这一温度范围内,某些合金表现出优良的超塑性,这已在Inoue [7]的工作中得以证实.在本试验条件下,合金即可能因高闪温的作用而处于过冷液相区温度范围内,从而在摩擦过程中产生大量塑性变形.成分相同的晶态合金的晶粒同晶粒之间的位相差会阻碍合金的塑性变形,合金磨损表面形成的裂纹更易扩展,裂纹扩展至一定程度后形成碎片并剥落,剥落的碎片在反复摩擦过程中被压碎并形成小尺寸磨屑,磨屑作为磨粒对合金产生犁削作用,从而使晶态合金磨损表面出现明显的犁沟.非晶合金硬度比晶态合金的低,相应的磨屑硬度亦较低,其对非晶合金磨损表面的犁削作用较弱,因此非晶合金磨损表面无明显的磨粒磨损迹象,但其塑性变形和塑性流动远比晶态合金的严重,这决定了其61摩 擦 学 学 报第23卷耐磨性较差.3 结论a . 所制备的6种非晶合金试样同GC r 15钢对摩时的摩擦系数处于0.5～0.6范围内,同非晶合金成分相同的4种晶态合金在相同试验条件下的摩擦系数处于0.4～0.5之内.b . 晶态合金的显微硬度和耐磨性比成分相同的非晶合金的高.c . 非晶与晶态合金的磨损机制有所不同,非晶合金主要以塑性流变为主,而晶态合金主要以脆性断裂和磨粒磨损为主.参考文献:[1] Inoue A ,Zhang T ,M asumo to T .Zr 2A l 2N iAmo rphous A lloysw ith H igh Glass T ransiti on T emperature and Significant Supercoo led L iquid R egi on [J ].M ater T rans J I M ,1990,31:1772183.[2] Inoue A ,N akam ura T ,N ish iyam a N ,et a l .M g 2Cu 2Y BulkAmo rphous A lloys w ith H igh T ensile Strength P roduced by a H igh 2P ressure D ie Casting M ethod [J ].M ater T rans J I M ,1992,33:9372945.[3] K linger R ,Feller H G .Sliding F ricti on and W ear R esistanceof the M etallic Glass Fe 40N i 40B 20[J ].W ear ,1983,86:2872297.[4]Yo sh itake N ish i,T sukuru Kai,Katsuh iro K itago.W earR esistance of Fe 2Co 2Si 2B A lloy Glasses [J ].W ear,1988,126:1912196.[5] Chen W R (陈伟荣),W ang Y M (王英敏),Q iang J B (羌建兵),et a l .T he E lectron Concentrati on 2Constant and A tom icSize 2Constant C riteri on in Zr 2Based Bulk M etallic Glasses (Zr基大块非晶合金的等电子浓度和等原子尺寸判据)[J ].Ch inese Journal of M aterials R esearch (材料研究学报),2002,16(2):2192224.[6] Xu G Z ,Zhou Z R ,L iu J J .A Comparative Study on F rettingW ear 2R esistant P roperties of I on 2P lated T i N and M agnetron 2Sputtered M oS 2Coatings [J ].W ear ,1999,224:2112215.[7]Inoue A .H igh Strength Bulk Amo rphous A lloys w ith L ow C ritical Coo ling R ates (O verview )[J ].M ater T rans J I M ,1995,36:8662875.Fr iction and W ear Character istics of Zr -based Bulk M etallic GlassesCH EN W ei 2rong1,2,W AN G Y ing 2m in 2,Q I AN G J ian 2b ing 2,XU W ei 2p ing 2,W AN G D e 2he 2,DON G Chuang 2,XU T ao 3,ZHAN G A i 2m in3(1.M echanical E ng ineering D ep art m ent ,D alian U niversity ,D alian 116622,Ch ina ;2.S tate K ey L aboratory f or M aterials M od if ication by L aser ,Ion and E lectron B eam s ,D alian U niversity of T echnology ,D alian 116024,Ch ina3.S tate K ey L aboratory of S olid L ubrication ,L anz hou Institu te of Che m ical P hy sics ,Ch inese A cad e m y of S ciences ,L anz hou 730000,Ch ina )Abstract :Six k inds of Zr 2based am o rp hou s alloys w ith differen t com po siti on s w ere designed and p repared acco rding to the ru les of con stan t electron concen trati on and con stan t atom ic size .T he fricti on and w ear characteristics of the am o rphou s alloys under dry sliding again st SA E 52100steel w ere investigated on an SRV fricti on and w ear tester ,in a ball 2on 2disc con tact configu rati on .T he fricti on and w ear behavi o r of fou r crystalline sp eci m en s w ith the sam e com po siti on s as the am o rp hou s coun terparts w as also evaluated under the sam e testing conditi on s as a com parison .T he w o rn su rface m o rp ho logies of the alloys w ere ob served w ith a scann ing electron m icro scope .R esu lts indicated that all the am o rphou s alloys had nearly the sam e fricti oncoefficien ts 0.5～0.6,w h ile the crystalline coun terp arts registered fricti on coefficien ts 0.4～0.5.T hecrystalline alloys show ed better w ear resistance than the am o rphou s coun terparts ,w h ich w as dependen t on the differen t w ear m echan is m s .In o ther w o rds ,the crystalline alloys w ere characterized by b rittle fractu re and ab rasive w ear ,w h ile the am o rphou s coun terparts w ere characterized by severe p lastic defo r m ati on and flow ing .Key words :Zr 2based alloy ;bu lk m etallic glass ;m icrohardness ;fricti on and w ear behavi o rAuthor :CH EN W ei 2rong ,fem ale ,bo rn in 1963,Ph .D .,A ssociate P rofesso r ,e 2m ail :rem iliu @m ail.dlp tt ...71第1期陈伟荣等: Zr 基大块非晶合金的摩擦磨损性能。
Zr基块体非晶合金的摩擦磨损行为
Trans. Nonferrous Met. Soc. China 22(2012) 585−589Dry sliding tribological behavior of Zr-based bulk metallic glassWU Hong 1, 2, Ian BAKER 2, LIU Yong 1, WU Xiao-lan 21. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;2. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755-8000, U.S.A.Received 9 September 2011; accepted 16 January 2012Abstract: The tribological behavior of a Zr-based bulk metallic glass (BMG) was investigated using pin-on-disk sliding measurements in two different environments, i.e., air and argon, against an yttria-stabilized zirconia counterface. It was found that the wear of the Zr-based BMG was reduced by more than 45% due to the removal of oxygen from the test environment at two different loads, i.e., 16 N and 23 N. The wear pins were examined using X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy and optical surface profilometry. A number of abrasive particles and grooves presented on the worn surface of the pin tested in air, while a relatively smooth worn surface was observed in the specimens tested in argon. The wear mechanism of the pin worn in air was dominated by abrasive wear compared with an adhesive wear controlled process in the tests performed in argon.Key words: bulk metallic glasses; tribological behavior; oxidation; wear mechanism1 IntroductionOver the past two decades the tribological properties of bulk metallic glasses (BMGs) have been of great attraction as promising candidates for high wear applications because of their comparatively high hardness and strength [1−3]. For instance, MA et al [4] used a Zr-based BMG as bearing rollers, which showed a better wear resistance than the commercial GCr15 steel. ISHIDA et al [5] reported a new type of Ni-based BMG microgear, which had a much longer lifetime of 2500 h compared with 8 h for SK-steel.Nonetheless, recent studies on the friction and wear behaviors of BMGs indicated contradictory performance [6,7]. Since BMGs are in a non-equilibrium state, their tribological behaviors are strongly dependent on the test conditions and local chemical compositions, such as applied load, sliding distance, sliding speed, friction mode [5], lubrication condition [7] as well as annealed state [6,8]. In addition, it is well-known that oxygen not only has adverse effects on the glass-forming ability and thermal stability [9], but also affects the deformability of BMGs [10]. Even though some studies reported that thefriction and wear of metallic glasses have shown sensitivity to oxygen in test environment, the underlying mechanism is not completely understood [11−14]. For example, some BMGs show a negative effect of oxidation on wear resistance [11,12], while others show a positive effect [13]. In the view of fundamental research and industrial application, therefore, it is of great importance to systematically characterize the tribological behavior of metallic glass and to reveal the related mechanism for sliding in different environments.This paper outlines our preliminary investigation on the friction and wear behavior of a Zr-based BMG during dry sliding in two different environments, air and argon.2 ExperimentalA master alloy with a nominal composition of Zr 52.5Cu 17.9Ni 14.6Al 10Ti 5 (mole fraction, %) was prepared by arc melting a mixture of pure Zr (99.8%, mass fraction), Cu (99.9%), Ni (99.9%), Al (99.99%), and Ti (99.9%) in a Ti-gettered high-purity argon atmosphere. The ingot was remelted four times to ensure a homogeneous composition, and then suction cast into 3 mm in diameter and 70 mm in length, in a water-cooledFoundation item: Project (DE-FG02-07ER46392) supported by U.S. Department of Energy, Office of Basic Energy Science; Project (2011JQ002) supportedby the Fundamental Research Funds for the Central Universities, China; Project supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University, ChinaCorresponding author: LIU Yong; Tel: +86-731-88830406; E-mail: yonliu11@ DOI: 10.1016/S1003-6326(11)61217-XWU Hong, et al/Trans. Nonferrous Met. Soc. China 22(2012) 585−589 586copper mold. Wear pins of 6 mm in length were cut from the suction-cast rods using a high speed abrasive saw, cooled with water to avoid possible crystallization. The two ends were polished with 600 grit silicon carbide papers and finished with 0.3 μm-alumina powders.Pin-on-disk tribotests were performed against an yttria-stabilized zirconia counterface material polished to a surface roughness of 0.01−0.05 μm. The test system was described in detail in Ref. [15]. Cylindrical pin specimens were fixed on a holder and loaded against the rotating disk. The tests were conducted under constant applied normal loads of 16 N and 23 N, at a sliding speed 1 m/s and for a sliding distance of 1 km, in air and argon. Three tests were performed in each environment.The phases of the specimens both before and after wear testing were analyzed on a Rigaku D/Max 2000 X-ray diffractometer (XRD) with Cu Kα radiation operated at 40 kV and 300 mA. Measurements were performed by step scanning 2θ from 10° to 120° with 0.02(°)/step. A count time of 1 s/step was used, giving a total scan time of ~1.5 h. The thermodynamic behavior of the wear pins was investigated on a Perkin Elmer DSC 7 differential scanning calorimeter (DSC), from room temperature to 600 °C at a heating rate of 20 °C/min under flowing argon. The worn surfaces were examined with an FEI XL−30 scanning electron microscope operating at 15 kV, equipped with an EDAX Li-drifted energy dispersive X-ray spectrometer. Worn surface topographies of the pins were determined using a Zygo 7300 profilometer. The mass loss of the specimens was measured in an electronic balance of ±0.1 mg precision before and after the wear test. The density of the metallic glass was determined according to Archimedes’ method and the mass loss was then converted to a volume loss value.3 Results and discussionThe mass loss results for the sliding tests run in both air and argon at two different loads are shown in Fig. 1. For a given load, it can be clearly seen that the wear loss of the pins is dramatically reduced by the removal of oxygen in the test environment. Wear rate in both environments increased with increasing normal load. As listed in Table 1, the wear loss of the pins after 1 km of sliding decreased by more than 45% when varying the environment from air to argon under both loads. This indicates the adverse effect of oxygen in the test environment on the wear resistance of BMG during sliding. A similar study conducted by FU et al [11], reported that less wear was obtained in a Zr-based BMG by changing the test environment from air to vacuum.The measured friction force was somewhat variable during the tests, and decreased from a higher initial value to a lower steady state value under all test conditions, as shown in Fig. 2. The steady state friction coefficient ranged from 0.15 to 0.28 depending on the normal load and the test environment. For a given load, the measured friction coefficient (steady state) was somewhat higher for tests conducted in air than that for tests performed in argon. These are considerably lower than the result of BLAU [7], and comparatively close to the values reported by LIU et al [16], in dry sliding tests of the same composition of BMG. Since the friction coefficient decreases with increasing load [11], the low friction coefficient obtained from the sliding tests may be ascribed to the high normal loads employed in theFig. 1 Wear loss (mean value of mass loss) of BMG specimens after 1 km-sliding tests in air and argon at different loads (Error bars signify standard deviations)Table 1 Wear loss of pins tested in air and argon at different loads (m denotes mean mass loss, V denotes volumetric loss, and μdenotes friction coefficient)Air Argon Load/Nm/mg V/mm3μm/mg V/mm3μ16 1.5 0.230.28 0.8 0.120.223 2.770.420.22 1.47 0.220.15Fig. 2 Friction coefficients as function of time during wear tests run for 1 km in air and argon under different loadsWU Hong, et al/Trans. Nonferrous Met. Soc. China 22(2012) 585−589 587present study. In addition, as there is no specific relationship between the friction coefficient and the wear loss [16], the friction coefficient cannot directly be used to be indicative of wear resistance for the BMG.XRD patterns of the pins before and after wear tests conducted in two different environments at a load of 23 N are shown in Fig. 3. A typical pattern of an amorphous structure with only a broad diffraction halo, and without any detectable sharp Bragg peaks corresponding to crystalline phases is present for as-cast BMG. For the pin wear-tested in air, several sharp Bragg diffraction peaks corresponding to three different crystal structures of ZrO2, i.e., cubic-ZrO2, tetragonal-ZrO2, and monoclinic- ZrO2, superimpose on a broad diffraction halo which corresponds to the remaining glassy matrix. These signify the coexistence of various crystalline phases and residual amorphous phase on the worn surface after sliding. However, there are still a few peaks that are difficult to be determined due to limited number of diffraction peaks. Based on the investigation of phases on the same composition BMG after annealing at temperature from 400 °C up to 550 °C reported by HE et al [17], there could be either Zr2Ni0.67O0.33, Zr2Cu, or ZrAl phases, but this needs to be confirmed by further study.Fig. 3 XRD patterns of pins before and after wear tests in different environments at load of 23 NDSC curves of the pins after wear tests in both environments at a load of 23 N are shown in Fig. 4. The DSC curve of as-cast BMG is included for comparison. No significant difference between the tested specimens and the untested specimen can be detected, indicating that there is no appreciable structural change in the pins after wear tests. FU and RIGNEY [12] compared the DSC curves of the wear debris generated in air and vacuum using different loads with the untested BMG specimen, and found a series of difference, including the absence of low temperature peaks, variation in shape for high temperature peak, and peak shifting with both load and environment. They conjectured that the potential reasons may be the further homogenization of the alloy and the redistribution of oxygen caused by sliding [12]. The decrease in the crystallization temperature of debris may be due to considerably increased surface [14]. However, similar examinations are not possible to be performed in the present study due to the insignificant amount of debris in all tests.Fig. 4 DSC curves of pins before and after wear tests in different environments at load of 23 NWorn surfaces of the pins wear tested in air and argon under different loads are shown in Fig. 5. Parallel grooves and abrasive particles are clearly observable in the pins tested in air under both loads (Figures 5(a) and (c)), showing a typical abrasive manner. Local plastic deformation can be found at the edge of the grooves in Fig. 5(c), which may be attributed to the higher normal load. Increasing the load leads to more adhesive wear in the BMG [16]. In contrast, for the tests in argon, evident plastic flow appears on the worn surface, and no grooves can be observed (Fig. 5(b)). Thus, the adhesive wear becomes the main mechanism. At the load of 23 N, a relatively smooth worn surface is present after smearing of the wear tracks (Fig. 5(d)), implying a mainly adhesive manner.The surface topographies produced in air and argon as determined by a non-contact optical surface profilometer are shown in Fig. 6. The average surface roughness, R a, of the pin tested in air was 3.474 μm, with some grooves as deep as 20 μm, while the worn surface generated in argon was smoother with an R a of 1.88 μm. This demonstrates once more that the worn surface of the pin tested in argon was smoother than that of the pin tested in air.The frictional heating occuring during the sliding process can induce both oxidation and crystallization in a BMG if temperature rise is sufficiently high. For the tests in air, a couple of oxides, e.g., monoclinic ZrO2 and tetragonal ZrO2, formed as a result of oxidation, were caused by frictional heating on the wear surface of the pin (see in Fig. 3). TRIWIKANTORO et al [18] studiedWU Hong, et al/Trans. Nonferrous Met. Soc. China 22(2012) 585−589588Fig. 5 Secondary electron images of worn surface of pins tested in air (a) and argon (b) at load of 16 N, and pins tested in air (c) and argon (d) at load of 23 NFig. 6 Worn surface topographies of pins wear tested in air (a) and argon (b) at load of 23 N determined by optical surface profilometer (Color bands signify the relative height of the profile. Grey lines denote the moving direction of the profilometer)the oxidation behavior in a series of Zr-based metallic glasses and found that the oxide scales formed during oxidation have a nanocrystalline microstructure consisting mainly of tetragonal and monoclinic ZrO2. It is worth noting that the zirconia disk has been shown to have a cubic crystal structure [19]. Thus, the cubic ZrO2 present on the worn surface of the pins supposed to be derived from the counterface. JIN et al [20] investigated the dry sliding wear characteristics of a Zr-based BMG at room temperature, and observed that the formation and subsequent peeling-off of oxygen-rich tribolayers during wear was the main wear mechanism in the as-cast and relaxed specimens. In the present study, the monoclinic ZrO2 and tetragonal ZrO2 formed on the pins were peeled off and subsequently acted as abrasive particles together with the cubic ZrO2 that debonded from the counterface during the wear process, thus resulting in the presence of long parallel grooves in the pins tested in air (Figs. 5(a) and (c)).For the tests in argon, the effect of oxidation can be ruled out owing to the removal of oxygen. Surface softening presumably occurred due to the combination of frictional heating and plastic deformation [16], and led to the appearance of plastic flow and smeared surface (Figs. 5(b) and (d)). LEE and EVETTS [14] noted that the development of the surface morphology of metallic glasses during sliding started at an initial stage, including low contact area, gradually increasing contact area occurring at asperities, and surface smoothing by a “smear-like” plastic deformation process, which allowed material to fill in the pits and holes between asperities, hence showing little wear debris. These features are quite similar to the observations of the pins tested in argon, implying that such initial stage during the wear process could be maintained by the exclusion of oxygen in the test environment.WU Hong, et al/Trans. Nonferrous Met. Soc. China 22(2012) 585−589 5894 Conclusions1) The wear of a Zr-based BMG against an yttria-stabilized zirconia counterface was studied using pin-on-disk wear tests in two different environments, i.e., air and argon, at two different loads of 16 N and 23 N. The results obtained are summarized as follows.2) The wear rate of the BMG pins was reduced significantly by the removal of oxygen from the test environment at both loads.3) A number of abrasive particles and grooves were presented on the worn surface of the pin tested in air, thus implying an abrasive wear controlled manner.4) A relatively smooth worn surface was observed in the specimens after tests conducted in argon, a feature attributed to the occurrence of adhesive wear. References[1]JOHNSON W L. Bulk glass-forming metallic alloys: Science andtechnology [J]. MRS Bull, 1999, 24: 42−56.[2]PARLAR Z, BAKKAL M, SHIH A H. Sliding tribologicalcharacteristics of Zr-based bulk metallic glass [J]. Intermetallics,2008, 16: 34−41.[3]GLORIANT T. Microhardness and abrasive wear resistance ofmetallic glasses and nanostructured composite materials [J]. J Non-cryst Solids, 2003, 316: 96−103.[4]MA M Z, LIU R P, XIAO Y, LOU D C, LIU L, WANG Q, WANG WK. Wear resistance of Zr-based bulk metallic glass applied in bearingrollers [J]. Mater Sci Eng A, 2004, 386: 326−330.[5]ISHIDA M, TAKEDA H, NISHIYAMA N, KITA K, SHIMIZU Y,SAOTOME Y, INOUE A. Wear resistivity of super-precision microgear made of Ni-based metallic glass [J]. Mater Sci Eng A,2007, 449−451: 149−154. [6]TAM C Y, SHEK C H. Abrasive wear of Cu60Zr30Ti10 bulk metallicglass [J]. Mater Sci Eng A, 2004, 384: 138−142.[7]BLAU P J. Friction and wear of a Zr-based amorphous metal alloyunder dry and lubricated conditions [J]. Wear, 2001, 250: 431−434. [8]LI G, WANG Y Q, WANG L M, GAO Y P, ZHANG R J, ZHAN Z J,SUN L L, ZHANG J. Wear behavior of bulk Zr41Ti14Cu12.5Ni10Be22.5metallic glasses [J]. J Mater Res 2002, 17: 1877−1880.[9]GEBERT A, ECKERT J, SCHULTZ L. Effect of oxygen on phaseformation and thermal stability of slowly cooled Zr65Al7.5Cu17.5Ni10metallic glass [J]. Acta Mater, 1998, 46: 5475−5482.[10]LU Z P, BEI H, WU Y, CHEN G L, GEORGE E P, LIU C T. Oxygeneffects on plastic deformation of a Zr-based bulk metallic glass [J].Appl Phys Lett, 2008, 92: 011915-1−011915-3.[11]FU X, KASAI T, FALK M L, RIGNEY D A. Sliding behavior ofmetallic glass: Part I. Experimental investigations [J]. Wear, 2001,250: 409−419.[12]FU X, RIGNEY D A. Tribological characteristics ofZr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass [J]. Mater Res SocSymp Proc, 1998, 554: 437−442.[13]MIYOSHI K, BUCKLEY D H. Microstructure and surface chemistryof amorphous alloys important to their friction and wear behavior [J].Wear, 1986, 110: 295−313.[14]LEE D H, EVETTS J E. Sliding friction and structural relaxation ofmetallic glasses [J]. Acta Metall, 1984, 32: 1035−1043.[15]JOHNSON B J, KENNEDY F E, BAKER I. Dry sliding wear ofNiAl [J]. Wear, 1996, 192: 241−247.[16]LIU Y, YITIAN Z, XUEKUN L, LIU Z. Wear behavior of a Zr-basedbulk metallic glass and its composites [J]. J Alloys Compd, 2010, 503:138−144.[17]HE G, BIAN Z, CHEN G L. Investigation of phases on a Zr-basedbulk glass alloy [J]. Mater Sci Eng A, 2000, 279, 237−243.[18]TRIWIKANTOR O, TOMA D, MEURIS M, KOSTER U. Oxidationof Zr-based metallic glasses in air [J]. J Non-cryst Solids, 1999,250−252: 719−723.[19]BAKER I, SUN Y, KENNEDY F E, MUNROE P R. Dry slidingwear of eutectic Al−Si [J]. J Mater Sci, 2010, 45: 969−978.[20]JIN H W, AYER R, KOO J Y, RAGHAV AN R, RAMAMURTY U.Reciprocating wear mechanisms in a Zr-based bulk metallic glass [J].J Mater Res, 2007, 22: 264−273.Zr基块体非晶合金的摩擦磨损行为吴宏1, 2，Ian BAKER2，刘咏1，吴晓蓝21. 中南大学粉末冶金国家重点实验室，长沙 410083；2. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755-8000, U.S.A.摘 要：采用销盘式摩擦实验研究Zr基块体非晶合金分别在空气与氩气环境中的摩擦磨损行为。
《2024年Zr50Cu50非晶合金变形行为的分子动力学模拟》范文
《Zr50Cu50非晶合金变形行为的分子动力学模拟》篇一一、引言非晶合金，又称金属玻璃，因其独特的结构和力学性能在材料科学领域备受关注。
Zr50Cu50非晶合金作为一种典型的非晶合金，其变形行为的研究对于理解非晶合金的力学性能和优化其应用具有重要意义。
近年来，随着计算机模拟技术的发展，分子动力学模拟成为研究非晶合金变形行为的有效手段。
本文利用分子动力学方法对Zr50Cu50非晶合金的变形行为进行模拟，以期揭示其变形机制和力学性能。
二、模型与方法1. 模型构建采用Zr50Cu50非晶合金的化学成分构建模型，通过快速冷却法生成非晶结构。
模型中包含Zr和Cu两种元素，原子间相互作用采用嵌入原子法进行描述。
2. 分子动力学方法采用分子动力学软件进行模拟，时间步长设置为1×10-15秒。
首先对模型进行能量最小化处理，以消除初始构型中的应力。
然后对模型施加外力，模拟非晶合金的变形过程。
三、模拟结果与分析1. 变形过程在模拟过程中，观察到Zr50Cu50非晶合金在受到外力作用时，原子发生重新排列，形成一系列的剪切带。
这些剪切带的形成和扩展是非晶合金变形的主要机制。
2. 剪切带形成与扩展剪切带的形成与扩展过程中，原子间的相互作用发生变化，导致局部区域的原子重新排列。
剪切带的形成是局部软化区域的结果，扩展过程中伴随着原子的流动和重排。
这些过程对非晶合金的力学性能具有重要影响。
3. 力学性能通过模拟得到Zr50Cu50非晶合金的应力-应变曲线。
结果表明，非晶合金在变形过程中表现出较高的塑性和韧性。
同时，发现非晶合金在变形过程中具有一定的强度和硬度。
这些结果与非晶合金的实际力学性能相符，表明模拟方法的有效性。
四、讨论与结论通过分子动力学模拟，揭示了Zr50Cu50非晶合金的变形行为和力学性能。
在变形过程中，剪切带的形成与扩展是主要的变形机制。
剪切带的形成和扩展过程中伴随着原子的重新排列和流动，导致非晶合金的塑性和韧性得以发挥。
《Zr65Cu35非晶合金结构及动力学的分子动力学模拟》范文
《Zr65Cu35非晶合金结构及动力学的分子动力学模拟》篇一一、引言非晶合金作为一种具有独特物理和化学特性的材料，近年来在材料科学领域受到了广泛关注。
Zr65Cu35非晶合金作为其中的一种典型代表，其结构特性和动力学行为的研究对于理解非晶合金的宏观性能具有重要的意义。
本文采用分子动力学模拟的方法，对Zr65Cu35非晶合金的结构及动力学进行了深入的研究。
二、分子动力学模拟方法分子动力学模拟是一种基于经典力学的计算机模拟方法，可以用于研究物质的微观结构和动力学行为。
在本文中，我们采用了一种适合非晶合金研究的分子动力学模拟方法。
该方法首先通过随机分布的方式生成Zr65Cu35合金的初始结构，然后通过逐步调整原子间的相互作用力，使系统达到平衡状态。
在模拟过程中，我们采用了合适的势能函数和温度控制方法，以保证模拟结果的准确性。
三、Zr65Cu35非晶合金的结构特性通过分子动力学模拟，我们得到了Zr65Cu35非晶合金的微观结构。
在非晶合金中，原子没有长程有序的排列，而是呈现出一种短程有序、长程无序的结构特点。
我们对模拟结果进行了进一步的分析，发现Zr65Cu35非晶合金中存在大量的五角多面体和紧密堆积的原子结构，这些结构是非晶合金具有高强度和高硬度的主要原因。
此外，我们还发现非晶合金中存在着一定的局域结构不均匀性，这种不均匀性对于非晶合金的力学性能和物理性能具有重要的影响。
四、Zr65Cu35非晶合金的动力学行为非晶合金的动力学行为是指其原子在微观尺度上的运动和相互作用过程。
通过分子动力学模拟，我们观察到Zr65Cu35非晶合金中原子在高温下的快速运动和在低温下的缓慢运动过程。
此外，我们还研究了非晶合金在受到外力作用时的原子响应过程，包括原子间的相互作用和应力传递等过程。
这些研究有助于我们深入理解非晶合金的力学性能和物理性能。
五、结论通过分子动力学模拟，我们研究了Zr65Cu35非晶合金的结构特性和动力学行为。