Effect of Grain Size on Nano-scratching Behavior of Polycrystallineγ-TiAl Alloy via Molecular Dynamics Simulation  

晶粒尺寸对多晶γ-TiAl合金表面纳米划痕行为影响的分子动力学模拟

作　　者：Cao Hui Xu Hanzong Li Haipeng Li Haiyan Chen Tao Feng Ruicheng 曹卉;徐汉宗;李海鹏;李海燕;陈涛;冯瑞成(兰州理工大学机电工程学院,甘肃兰州730050;兰州理工大学有色冶金新装备教育部工程研究中心,甘肃兰州730050;云南文山铝业有限公司,云南文山663000;常州大学机械与轨道交通学院,江苏常州213164)

机构地区：[1]School of Mechanical and Electrical Engineering,Lanzhou University of Technology,Lanzhou 730050,China [2]Engineering Research Center of Nonferrous Metallurgys New Equipment,Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China [3]Yunnan Wenshan Aluminum Co.,Ltd,Wenshan 663000,China [4]School of Mechanical Engineering and Rail Transit,Changzhou University,Changzhou 213164,China

出　　处：《稀有金属材料与工程》2025年第3期569-580,共12页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(52065036,52365018);Natural Science Foundation of Gansu(23JRRA760);Hongliu Outstanding Youth Foundation of Lanzhou University of Technology;China Postdoctoral Science Foundation(2023M733583)。

摘　　要：The scratching mechanism of polycrystallineγ-TiAl alloy was investigated at the atomic scale using the molecular dynamics method,with a focus on the influence of different grain sizes.The analysis encompassed tribological characteristics,scratch morphology,subsurface defect distribution,temperature variations,and stress states during the scratching process.The findings indicate that the scratch force,number of recovered atoms,and pile-up height exhibit abrupt changes when the critical size is 9.41 nm due to the influence of the inverse Hall-Petch effect.Variations in the number of grain boundaries and randomness of grain orientation result in different accumulation patterns on the scratch surface.Notably,single crystal materials and those with 3.73 nm in grain size display more regular surface morphology.Furthermore,smaller grain size leads to an increase in average coefficient of friction,removed atoms number,and wear rate.While it also causes higher temperatures with a larger range of distributions.Due to the barrier effect of grain boundaries,smaller grains exhibit reduced microscopic defects.Additionally,average von Mises stress and hydrostatic compressive stress at the indenter tip decrease as grain size decreases owing to grain boundary obstruction.基于分子动力学的方法,从原子尺度研究了不同晶粒尺寸影响下的多晶γ-TiAl合金表面划痕机理,分析了划痕过程中的力学特性、划痕形貌、微观缺陷分布以及温度和应力状态。结果表明,由于逆霍尔佩奇效应的影响,划痕力、原子回弹数量和堆积高度在临界尺寸为9.41 nm时出现突变。晶界数量的差异以及晶粒的晶粒取向随机性导致划痕表面堆积不同,其中单晶材料和晶粒尺寸为3.73 nm情况下的表面形貌更加规则。此外,晶粒尺寸越小,平均摩擦系数、原子去除数量以及特殊磨损率随之增加,温度的数值和分布范围更大。由于晶界的阻碍作用,小尺寸的晶粒有更少的微观缺陷,并且压头尖端处的平均冯.米塞斯应力和静水压应力随着晶粒尺寸的减小而减小。

关 键 词：grain size nano-scratching surface generation subsurface defect polycrystallineγ-TiAl alloy 

分 类 号：TG146.2[一般工业技术—材料科学与工程]