Minimum energy path of a solute atom diffusing to an edge dislocation core in Al-Mg alloys based on empirical atomic potential

LI Xiao-tong; TANG Xiao-zhi; GUO Ya-fang

doi:10.13374/j.issn2095-9389.2019.07.008

Volume 41 Issue 7

Jul. 2019

Turn off MathJax

Article Contents

Article Navigation > Chinese Journal of Engineering > 2019 > 41(7): 898-905

LI Xiao-tong, TANG Xiao-zhi, GUO Ya-fang. Minimum energy path of a solute atom diffusing to an edge dislocation core in Al-Mg alloys based on empirical atomic potential[J]. Chinese Journal of Engineering, 2019, 41(7): 898-905. doi: 10.13374/j.issn2095-9389.2019.07.008

Citation:

LI Xiao-tong, TANG Xiao-zhi, GUO Ya-fang. Minimum energy path of a solute atom diffusing to an edge dislocation core in Al-Mg alloys based on empirical atomic potential[J]. Chinese Journal of Engineering, 2019, 41(7): 898-905. doi: 10.13374/j.issn2095-9389.2019.07.008

Citation:

PDF( 3469 KB)

Minimum energy path of a solute atom diffusing to an edge dislocation core in Al-Mg alloys based on empirical atomic potential

doi: 10.13374/j.issn2095-9389.2019.07.008

1.
Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044, China
2.
National Experimental Teaching Demonstration Center for Civil Engineering, Beijing Jiaotong University, Beijing 100044, China

More Information

Corresponding author: GUO Ya-fang, E-mail: yfguo@bjtu.edu.cn
Received Date: 2018-06-20
Publish Date: 2019-07-01

Abstract

Abstract

Al-Mg alloys are widely used in manufacturing. But at specific temperatures and strain rates, their plastic instability is not conducive to processing applications. The microscopic mechanism of plastic instability is the interaction between solute atoms and dislocations which induce a pinning-unpinnning effect. This effect, reflected on the microscopic scale, is also called dynamic strain aging (DSA). The DSA phenomenon causes negative strain-rate sensitivity and leads to plastic instability, which is harmful to its production. In this paper, the climbing image nudged elastic band method was adopted to explore the transition states along the minimum potential energy path, revealing a detailed evolution of atomic structures. The interaction range relies on the relative position and energy barrier of the transition, when a substitutional solute diffuses to an edge dislocation core in its stress field. Both substitution and vacancy-assisted migration are considered. The thermal activation time required for diffusion was estimated using transition state theory. The results indicate that there is no obvious law of solute atom migration in the compressive stress field. However, with the distance of the solute atom and the dislocation shortening, the migration potential energy barrier and the total energy of the system were gradually reduced. The present widespread empirical atomic potential can well estimate the phenomenon that the solute atom is prone to gathering in the tensile stress field. The transition states of migration confirmed the microstructure changes, depending on the position of the solute atom. The interaction region was no more than 2 nm. The migration energy was significantly reduced by vacancy mechanism, and the corresponding thermal activation time was shortened to microseconds. When the solute atoms finally migrated and stabilized near the dislocation core, there existed a maximum linear density. That is to say a dense arrangement along the dislocation line was not energetically preferred.
- aluminum magnesium alloy,
- solute atom,
- dislocation,
- diffusing,
- migration energy

FullText(HTML)

References(20)

References

[1]	Portevin A, Le Chatelier F. Sur un phénomène observé lors de l'essai de traction d'alliages en cours de transformation. Comptes Rendus de l'Académie des Sciences Paris, 1923, 176: 507
[2]	Araki H, Saji S, Okabe T, et al. Solidation of mechanically alloyed Al-10.7%Ti powder at low temperature and high pressure of 2 GPa. Mater Trans JIM, 1995, 36(3): 465 doi: 10.2320/matertrans1989.36.465
[3]	彭開萍, 陳文哲, 錢匡武. 3004鋁合金"反常"鋸齒屈服現象的研究. 物理學報, 2006, 55(7): 3569 doi: 10.3321/j.issn:1000-3290.2006.07.061 Peng K P, Chen W Z, Qian K W. Study of an anomalous serrated yielding phenomenon in 3004 aluminum alloy. Acta Phys Sin, 2006, 55(7): 3569 doi: 10.3321/j.issn:1000-3290.2006.07.061
[4]	Van den Beukel A. Theory of the effect of dynamic strain aging on mechanical properties. Phys Status Solidi A, 1975, 30(1): 197 doi: 10.1002/pssa.2210300120
[5]	Sun L, Zhang Q C, Cao P T. Influence of solute cloud and precipitates on spatiotemporal characteristics of Portevin-Le Chatelier effect in A2024 aluminum alloys. Chin Phys B, 2009, 18(8): 3500 doi: 10.1088/1674-1056/18/8/061
[6]	曹鵬濤, 張青川, 肖銳, 等. 紅外測溫法研究Al-Mg合金中的Portevin-Le Chatelier效應. 物理學報, 2009, 58(8): 5591 doi: 10.3321/j.issn:1000-3290.2009.08.071 Cao P T, Zhang Q C, Xiao R, et al. The Portevin-Le Chatelier effect in Al-Mg alloy investigated by infrared pyrometry. Acta Phys Sin, 2009, 58(8): 5591 doi: 10.3321/j.issn:1000-3290.2009.08.071
[7]	高越, 符師樺, 蔡玉龍, 等. 數字剪切散斑干涉法研究鋁合金中Portevin-Le Chatelier帶的離面變形行為. 物理學報, 2014, 63(6): 066201-1 https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201406028.htm Gao Y, Fu S H, Cai Y L, et al. Digital shearography investigation on the out-plane deformation of the Portevin-Le Chatelier bands. Acta Phys Sin, 2014, 63(6): 066201-1 https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB201406028.htm
[8]	王中光, 黃元士, 葛庭燧. 在鋁鎂合金的疲勞載荷過程中溶質原子與位錯的交互作用. 物理學報, 1965, 21(6): 1253 https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB196506014.htm Wang Z G, Huang Y S, Ge T S. Interaction of solute atoms with dislocations in aluminum-magnesium alloys under fatigue loading. Acta Phys Sin, 1965, 21(6): 1253 https://www.cnki.com.cn/Article/CJFDTOTAL-WLXB196506014.htm
[9]	Aboulfadl H, Deges J, Choi P, et al. Dynamic strain aging studied at the atomic scale. Acta Mater, 2015, 86: 34 doi: 10.1016/j.actamat.2014.12.028
[10]	林均品. Mg含量對Al-Mg合金動態再結晶的影響. 北京科技大學學報, 1997, 19(1): 47 https://www.cnki.com.cn/Article/CJFDTOTAL-BJKD199701008.htm Lin J P. Effect of Mg content on dynamic recrystallization behaviours of Al-Mg alloys. J Univ Sci Technol Beijing, 1997, 19(1): 47 https://www.cnki.com.cn/Article/CJFDTOTAL-BJKD199701008.htm
[11]	Keralavarma S M, Bower A F, Curtin W A. Quantum-to-continuum prediction of ductility loss in aluminium-magnesium alloys due to dynamic strain aging. Nature Commun, 2014, 5: 4604 doi: 10.1038/ncomms5604
[12]	杜海龍, 陳忠家. 鋁鎂合金中溶質分布形態的分子動力學研究. 合肥工業大學學報(自然科學版), 2011, 34(3): 346 doi: 10.3969/j.issn.1003-5060.2011.03.006 Du H L, Chen Z J. Molecular dynamics investigation on the distribution morphology of solute atoms in Al-Mg alloy. J Hefei Univ Technol Nat Sci, 2011, 34(3): 346 doi: 10.3969/j.issn.1003-5060.2011.03.006
[13]	Curtin W A, Olmsted D L, Hector Jr L G. A predictive mechanism for dynamic strain ageing in aluminium-magnesium alloys. Nature Mater, 2006, 5(11): 875 doi: 10.1038/nmat1765
[14]	Lebyodkin M, Dunin-Barkowskii L, Brechet Y, et al. Spatio-temporal dynamics of the Portevin-Le Chatelier effect: experiment and modelling. Acta Mater, 2000, 48(10): 2529 doi: 10.1016/S1359-6454(00)00067-7
[15]	何艷生, 符師樺, 張青川. 不同加載條件下位錯和溶質原子交互作用的數值模擬. 物理學報, 2014, 63(22): 228102-1 doi: 10.7498/aps.63.228102 He Y S, Fu S H, Zhang Q C. Simulations of the interactions between dislocations and solute atoms in different loading conditions. Acta Phys Sin, 2014, 63(22): 228102-1 doi: 10.7498/aps.63.228102
[16]	Fan Y, Osetskiy Y N, Yip S, et al. Mapping strain rate dependence of dislocation-defect interactions by atomistic simulations. Proc Natl Acad Sci USA, 2013, 110(44): 17756 doi: 10.1073/pnas.1310036110
[17]	Tang X Z, Guo Y F, Sun L X, et al. Strain rate effect on dislocation climb mechanism via self-interstitials. Mater Sci Eng A, 2018, 713: 141 doi: 10.1016/j.msea.2017.12.002
[18]	Yan X, Sharma P. Time-scaling in atomistics and the rate-dependent mechanical behavior of nanostructures. Nano Lett, 2016, 16(6): 3487 doi: 10.1021/acs.nanolett.6b00117
[19]	江慧豐, 張青川, 陳學東, 等. 位錯與溶質原子間動態相互作用的數值模擬研究. 物理學報, 2007, 56(6): 3388 doi: 10.3321/j.issn:1000-3290.2007.06.057 Jiang H F, Zhang Q C, Chen X D, et al. Numerical simulation of the dynamic interactions between dislocation and solute atoms. Acta Phys Sin, 2007, 56(6): 3388 doi: 10.3321/j.issn:1000-3290.2007.06.057
[20]	Liu X Y, Ohotnicky P P, Adams J B, et al. Anisotropic surface segregation in Al-Mg alloys. Surf Sci, 1997, 373(2-3): 357 doi: 10.1016/S0039-6028(96)01154-5