罗德春,付蓉,张玲,曹卉,芮执元.纳米单晶γ-TiAl合金应变率效应的分子动力学模拟[J].稀有金属材料与工程,2018,47(3):853~859.[LUO De-chun,FU Rong,Zhang ling,CAO Hui,RUI Zhi-yuan.The nano Single crystal gamma - TiAl alloy strain rate effect of molecular dynamics simulation[J].Rare Metal Materials and Engineering,2018,47(3):853~859.]
纳米单晶γ-TiAl合金应变率效应的分子动力学模拟
投稿时间:2016-01-14  修订日期:2016-05-03
中文关键词:  γ-TiAl合金  应变率  分子动力学  裂纹扩展
基金项目:国家自然科学基金(51065014)
中文摘要:
      采用分子动力学方法模拟不同应变率下纳米单晶γ-TiAl合金中裂纹的扩展,利用速度加载方式对预置裂纹的单晶γ-TiAl合金进行动态单向拉伸,模拟过程中施加应变率为5.0*107S-1~7.5*109 S-1。研究结果表明:不同的应变率范围下裂纹的扩展形式差异很大。在不敏感区(≤4*108S-1),裂纹呈解理扩展;在敏感区(4.0*108S-1<应变率≤1.0*109S-1),前期呈现解理扩展特征,后期裂纹扩展通过裂尖发射滑移位错,位错塞积萌生空洞,空洞形核长大形成子裂纹,应变率≤5.0*108 S-1时,子裂纹发生偏向,与主裂纹呈45度方向串接,5.0*108 S-1<应变率≤1.0*109S-1时,子裂纹与主裂纹同向串接,最终导致裂纹扩展直至断裂;在突变区(≥1.0*109 S-1),因应变强化作用使裂纹不在应力最大时刻启裂,出现裂纹扩展后应力持续增加一段时间后减小的现象,高应变率导致裂尖前端多处区域的原子结构局部非晶化,最终在原子结构混乱处萌生微裂纹,微裂纹扩展导致“试件”多处开裂。
The nano Single crystal gamma - TiAl alloy strain rate effect of molecular dynamics simulation
英文关键词:gamma-TiAl alloy  strain rate  molecular dynamics  crack propagation
英文摘要:
      The propagation form of the preset edge crack in The nano Single crystal gamma-TiAl under different strain rate were simulated by the method of molecular dynamics in this paper, velocity loading way was used to obtain dynamic uniaxial tensile for preset edge crack in the single crystal gamma-TiAl within 5.0*107S-1~7.5*109 S-1. The results showed that the crack propagation form varies with the range of strain rate. In the non-sensitive region(≤4*108 S-1), the crack propagates in a brittle cleavage manner. In the sensitive region(4.0*108 S-1<the strain≤1.0*109 S-1), it was cleavage extension features Early,the slip dislocation was emitted from the crack tip, and the void defect initiates the place where dislocation piled up and then growed to the child crack later,the child crack linked the main crack when it biased 45-degree under the strain≤5.0*108 S-1,but it connected the main crack at the same direction under 5.0*108 S-1<the strain≤1.0*109 S-1,thus leaded to the fracture both finally; In the sharp-change region(≥1.0*109 S-1), the crack didnt craze in the maximum stress for the reinforcement of strain,and the Stress decreased for it continues to increase some time. The non-crystallizing of the atom structure occurs near the crack tip because of high strain rate, and then the micro crack initiates in area of structure disordered, the micro crack growth leads to the “test specimen” fracture eventually.
作者单位E-mail
罗德春 兰州理工大学 机电工程学院 astrobert@lut.cn 
付蓉 兰州理工大学 机电工程学院  
张玲 兰州工业学院 机电工程学院  
曹卉 兰州理工大学 机电工程学院  
芮执元 兰州理工大学 机电工程学院  
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