7S-1~7.5*109 S-1。研究結(jié)果表明:不同的應(yīng)變率范圍下裂紋的擴(kuò)展形式差異很大。在不敏感區(qū)(≤4*108S-1),裂紋呈解理擴(kuò)展;在敏感區(qū)(4.0*108S-1<應(yīng)變率≤1.0*109S-1),前期呈現(xiàn)解理擴(kuò)展特征,后期裂紋擴(kuò)展通過裂尖發(fā)射滑移位錯,位錯塞積萌生空洞,空洞形核長大形成子裂紋,應(yīng)變率≤5.0*108 S-1時,子裂紋發(fā)生偏向,與主裂紋呈45度方向串接,5.0*108 S-1<應(yīng)變率≤1.0*109S-1時,子裂紋與主裂紋同向串接,最終導(dǎo)致裂紋擴(kuò)展直至斷裂;在突變區(qū)(≥1.0*109 S-1),因應(yīng)變強(qiáng)化作用使裂紋不在應(yīng)力最大時刻啟裂,出現(xiàn)裂紋擴(kuò)展后應(yīng)力持續(xù)增加一段時間后減小的現(xiàn)象,高應(yīng)變率導(dǎo)致裂尖前端多處區(qū)域的原子結(jié)構(gòu)局部非晶化,最終在原子結(jié)構(gòu)混亂處萌生微裂紋,微裂紋擴(kuò)展導(dǎo)致“試件”多處開裂。"/>

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納米單晶γ-TiAl合金應(yīng)變率效應(yīng)的分子動力學(xué)模擬
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蘭州理工大學(xué) 機(jī)電工程學(xué)院,蘭州理工大學(xué) 機(jī)電工程學(xué)院,蘭州工業(yè)學(xué)院 機(jī)電工程學(xué)院,蘭州理工大學(xué) 機(jī)電工程學(xué)院,蘭州理工大學(xué) 機(jī)電工程學(xué)院

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中圖分類號:

TG146.23; O346.1

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國家自然科學(xué)基金(51065014)


The nano Single crystal gamma - TiAl alloy strain rate effect of molecular dynamics simulation
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College of Mechano-Electronical Engineering,Lanzhou Univ of Tech,College of Mechano-Electronical Engineering,Lanzhou Univ of Tech,Lanzhou institute of industrial,Lanzhou Univ of Tech,College of Mechano-Electronical Engineering,Lanzhou Univ of Tech,College of Mechano-Electronical Engineering,Lanzhou Univ of Tech

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    摘要:

    采用分子動力學(xué)方法模擬不同應(yīng)變率下納米單晶γ-TiAl合金中裂紋的擴(kuò)展,利用速度加載方式對預(yù)置裂紋的單晶γ-TiAl合金進(jìn)行動態(tài)單向拉伸,模擬過程中施加應(yīng)變率為5.0*107S-1~7.5*109 S-1。研究結(jié)果表明:不同的應(yīng)變率范圍下裂紋的擴(kuò)展形式差異很大。在不敏感區(qū)(≤4*108S-1),裂紋呈解理擴(kuò)展;在敏感區(qū)(4.0*108S-1<應(yīng)變率≤1.0*109S-1),前期呈現(xiàn)解理擴(kuò)展特征,后期裂紋擴(kuò)展通過裂尖發(fā)射滑移位錯,位錯塞積萌生空洞,空洞形核長大形成子裂紋,應(yīng)變率≤5.0*108 S-1時,子裂紋發(fā)生偏向,與主裂紋呈45度方向串接,5.0*108 S-1<應(yīng)變率≤1.0*109S-1時,子裂紋與主裂紋同向串接,最終導(dǎo)致裂紋擴(kuò)展直至斷裂;在突變區(qū)(≥1.0*109 S-1),因應(yīng)變強(qiáng)化作用使裂紋不在應(yīng)力最大時刻啟裂,出現(xiàn)裂紋擴(kuò)展后應(yīng)力持續(xù)增加一段時間后減小的現(xiàn)象,高應(yīng)變率導(dǎo)致裂尖前端多處區(qū)域的原子結(jié)構(gòu)局部非晶化,最終在原子結(jié)構(gòu)混亂處萌生微裂紋,微裂紋擴(kuò)展導(dǎo)致“試件”多處開裂。

    Abstract:

    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.

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羅德春,付蓉,張玲,曹卉,芮執(zhí)元.納米單晶γ-TiAl合金應(yīng)變率效應(yīng)的分子動力學(xué)模擬[J].稀有金屬材料與工程,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.]
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  • 收稿日期:2016-01-14
  • 最后修改日期:2016-05-03
  • 錄用日期:2016-05-18
  • 在線發(fā)布日期: 2018-04-11
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