Based on the average lattice and average atom models, effects of interstitial impurities on the valence electron structures and phase transformation of Ti-Al alloys are analyzed, and the degree of descen- sion 01 bond energy, melting point and liquidus temperatures as affected by interstitial impurities are calcu?lated by the bond energy formula of the EET. Those chief experimental results about phase transformation in Ti-Al alloys that are still in some dispute today are then explained. It is shown that, as a result of the in?terstitial impurities, the number of atomic states increases, bond structures become seriously anisotropic, β -> α transformation becomes hindered, and the phase transformation in the intermediate content becomes very complex. Also, the melting point and liquidus temperatures tend to decrease, for which the average decrease can be estimated through approximation by the EET.
Key words
Ti-Al alloy /
phase transformation /
valence electron structure /
interstitial impurities
{{custom_keyword}} /
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] 仲增墉.金属问化合物.北京:机械エ业出版社,1992.1~9
[2] Yoo M H et al. Deformation and fracture of mtermetallics. Acta Metall Mater, 1993，41(4):987
[3] McCullough C et al. Phase equilibria and solidification in Ti-Al al?loys. Acta MetaU, 1989,37(5) ： 1321
[4] Murray J L. Binary titanium phase diagrams. Onio： Metal Park, 1987.12?18
[5] He L L et al. I ne structure of the TizAl phase, and its relationship with IiAl and 113Al phases in the intermetallic compound AI51.7. Mater Lett, 1994,19(3) ： 17
[6] Anderson C D et al. Liquidus temperature in the Ti-Al system. Met Trans A, 1993,24A：61
[7] 张瑞林.固体与分子经验理论.长春:吉林科技出版社，1993.
[8] 李文等.Ti-Al系金属间化合物价电子结构与力学性能的关系.物 理学报，1998，47(11) :1865
[9] Nakamura M et al. environmental efiect on mechanical properties of TiAl base alloys. J Mater Res, 1993, 8(1) ：68
[10] Thomposon A W. Effects of hydrogen in titanium aiumimaes alloy. Mater Sci Eng, 1992, A153 ? 578
[11] Yang K et al. Effect of hydrogen as a temporary alloying element on the microstructure of a TisAl intermetallic. Scr Metall Mater 1993,28:71
[12] 李文等.Ti-Al相图的高温液相线.应用科学学报，1996，14(4): 391
[13] Carlson ON et al. Effects of interstitial impurities on phase equilib?ria. Bulletin of Alloy Phase Diagrams, 1987, 8(3) :208
{{custom_fnGroup.title_en}}
Footnotes
{{custom_fn.content}}
