基于努氏硬度表征大块金属玻璃的力学性能  

Characterization of Mechanical Properties of Bulk Metallic Glasses Based on Knoop Hardness

作　　者：刘明 郑强 高诚辉[1] Ming Liu;Qiang Zheng;Chenghui Gao(School of Mechanical Engineering and Automation,Fuzhou University,Fuzhou,350116)

机构地区：[1]福州大学机械工程及自动化学院,福州350116

出　　处：《固体力学学报》2021年第4期376-392,共17页Chinese Journal of Solid Mechanics

基　　金：国家自然科学基金项目(51705082,51875106);CAD/CAE福建省高校工程研究中心开放基金(K201705)资助。

摘　　要：采用多种载荷对14种大块金属玻璃进行努氏硬度测试,结果表明努氏硬度随载荷的增加而降低,最后趋于稳定,即材料受到正压痕尺寸效应的影响,并利用Meyer定律、弹塑性变形模型、Hays-Kendall模型和比例试样阻力模型对这种现象进行了解释,因此在压痕表面未产生裂纹时应采用较大载荷下趋于稳定的硬度值对杨氏弹性模量E和屈服强度σy进行分析.对于大多数实验材料,Marshall模型和Conway模型计算的弹性模量偏大.Marshall模型中的拟合参数α随着短对角线弹性恢复后的长度与长对角线的比值b′/d的增大而线性减小,Conway模型中的修正系数β随着压痕短对角线恢复前与恢复后长度比值的平方(b′/b)^(2)线性增加;对这两种模型进行修正时,α和β可分别用b′/d与(b′/b)^(2)线性表示.材料的努氏硬度和杨氏弹性模量成正比,比例系数为0.0445.分别利用Tabor、Lockett、Yu、Marsh、Johnson和Vandeperre模型计算屈服强度时,除Johnson模型的计算值接近实际值外,其它模型的计算结果偏小,修正努氏硬度HK与名义硬度H之间的比例关系能够使不同的模型计算出正确的屈服强度.当大块金属玻璃的努氏硬度小于6 GPa、玻璃态转变温度Tg小于800 K时,缺口韧性KQ随着努氏硬度或玻璃态转变温度线性增加.Hardness,elastic modulus and yield strength are very important mechanical properties of bulk metallic glasses.However,the traditional test methods are costly,time consuming and destructive.Considering the indentation size effect of bulk metallic glasses,the relationship among Knoop hardness,Young’s modulus,yield strength and notch toughness was studied systematically,and the mechanical properties of bulk metallic glasses were characterized based on Knoop hardness.14 bulk metallic glasses were investigated using the Knoop indenter under different normal loads.The results showed that Knoop hardness decreased with the increase of load,and approached to a constant value.A positive indentation size effect was found and analyzed using different theoretical models,including Meyer’s law,the elastic-plastic deformation model,the Hays-Kendall model,and the proportional specimen resistance model.The asymptotic value of Knoop hardness obtained under large loads in the absence of surface crack was used to calculate elastic modulus E and yield stress σy.The values of elastic modulus obtained by Marshall’s model and Conway’s model were larger than the reasonable ones.The fitting parameterαin Marshall’s model linearly decreased with the increase of the ratio between the short diagonal b′and the long diagonal d of residual indentation,and the correction factor β in Conway’s model linearly increased with the square of length ratio,(b′/b)^(2),where b is the short diagonal of indentation before elastic recovery.Modified models were proposed with α and β being expressed as linear functions of b′/d and(b′/b)^(2),respectively.Knoop hardness was found to be proportional to elastic modulus with the proportionality being 0.0445.Values of yield stress calculated by the models of Tabor,Lockett,Yu,Marsh,Johnson and Vandeperre were all smaller than the true values,among which,the values calculated by Johnson’s model was closest to the true values.The scaling relationship between Knoop hardness HK and nominal hardnes

关 键 词：大块金属玻璃 努氏硬度 压痕尺寸效应 杨氏弹性模量 屈服强度 缺口韧性 

分 类 号：TG139.8[一般工业技术—材料科学与工程]