On the abnormal fast diffusion of solute atoms in alpha-Ti: A first-principles investigation

CORC > 金属研究所 > 中国科学院金属研究所

	On the abnormal fast diffusion of solute atoms in alpha-Ti: A first-principles investigation
	Zhang, LJ; Chen, ZY; Hu, QM; Yang, R; Hu, QM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Liaoning, Peoples R China.
刊名	JOURNAL OF ALLOYS AND COMPOUNDS
	2018-04-05
卷号	740 页码:156-166
关键词	Grain-boundary Segregation Austenitic Stainless-steel Total-energy Calculations Augmented-wave Method Elastic Band Method Alloying Elements Self-diffusion Impurity Diffusion 1st Principles Saddle-points
ISSN号	0925-8388
英文摘要	Solute atoms such as Fe, Co, and Ni diffuse abnormally fast in alpha-Ti, which influences significantly the mechanical properties of the titanium alloys. Various mechanisms (e.g., the interstitial diffusion mechanism and solute-vacancy complex mechanism) have been proposed to account for the fast diffusion of these solutes in alpha-Ti. To elucidate such diffusion mechanism, a first-principles method is employed to calculate the formation energies, migration energy barriers, and solute-vacancy binding energies of the substitutional and interstitial solute atoms including Al, Si, Sn, V, Mn, Fe, Co, Ni, and Cu in alpha-Ti. Based on the calculated parameters, the diffusion mechanisms are discussed. Comparing the formation energies of the substitutional and interstitial solutes, we find that all the solute atoms prefer the substitutional configuration to the interstitial one. The interstitial migration energy barriers are quite low for all the solutes. Al and Sn diffuse mainly through normal vacancy mediated mechanism due to the high substitutional to interstitial preferential energy that leads to very low fraction of interstitial solutes (about 10(-15) similar to 10(-16) at 1000 K) at thermal equilibrium state and high interstitial diffusion activation energy. The 3d metal solute atoms, especially Mn, Fe, and Co, are fast diffusers and the diffusion coefficients are dominated by the interstitial mechanism because of their sizable thermal equilibrium interstitial fractions (several percent at 1000 K). The solute-vacancy complex mechanism is not likely to account for the fast diffusions in alpha-Ti. We show that the direct chemical interaction between the solute and matrix atoms determines the site-occupancy of the solute atoms in alpha-Ti besides the atomic size effect that was commonly believed to be responsible for the fast diffusions. (C) 2018 Elsevier B.V. All rights reserved.; Solute atoms such as Fe, Co, and Ni diffuse abnormally fast in alpha-Ti, which influences significantly the mechanical properties of the titanium alloys. Various mechanisms (e.g., the interstitial diffusion mechanism and solute-vacancy complex mechanism) have been proposed to account for the fast diffusion of these solutes in alpha-Ti. To elucidate such diffusion mechanism, a first-principles method is employed to calculate the formation energies, migration energy barriers, and solute-vacancy binding energies of the substitutional and interstitial solute atoms including Al, Si, Sn, V, Mn, Fe, Co, Ni, and Cu in alpha-Ti. Based on the calculated parameters, the diffusion mechanisms are discussed. Comparing the formation energies of the substitutional and interstitial solutes, we find that all the solute atoms prefer the substitutional configuration to the interstitial one. The interstitial migration energy barriers are quite low for all the solutes. Al and Sn diffuse mainly through normal vacancy mediated mechanism due to the high substitutional to interstitial preferential energy that leads to very low fraction of interstitial solutes (about 10(-15) similar to 10(-16) at 1000 K) at thermal equilibrium state and high interstitial diffusion activation energy. The 3d metal solute atoms, especially Mn, Fe, and Co, are fast diffusers and the diffusion coefficients are dominated by the interstitial mechanism because of their sizable thermal equilibrium interstitial fractions (several percent at 1000 K). The solute-vacancy complex mechanism is not likely to account for the fast diffusions in alpha-Ti. We show that the direct chemical interaction between the solute and matrix atoms determines the site-occupancy of the solute atoms in alpha-Ti besides the atomic size effect that was commonly believed to be responsible for the fast diffusions. (C) 2018 Elsevier B.V. All rights reserved.
学科主题	Chemistry, Physical ; Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
语种	英语
资助机构	National Key Basic Research Program [2014CB644001]; National Key Research and Development Program of China [2016YFB0701301]; National Natural Science Foundation of China [51271181, 51171187]
公开日期	2018-06-05
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/79373]
专题	金属研究所_中国科学院金属研究所
通讯作者	Hu, QM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Liaoning, Peoples R China.
推荐引用方式 GB/T 7714	Zhang, LJ,Chen, ZY,Hu, QM,et al. On the abnormal fast diffusion of solute atoms in alpha-Ti: A first-principles investigation[J]. JOURNAL OF ALLOYS AND COMPOUNDS,2018,740:156-166.
APA	Zhang, LJ,Chen, ZY,Hu, QM,Yang, R,&Hu, QM .(2018).On the abnormal fast diffusion of solute atoms in alpha-Ti: A first-principles investigation.JOURNAL OF ALLOYS AND COMPOUNDS,740,156-166.
MLA	Zhang, LJ,et al."On the abnormal fast diffusion of solute atoms in alpha-Ti: A first-principles investigation".JOURNAL OF ALLOYS AND COMPOUNDS 740(2018):156-166.