复相Al3Ti—8Mn基合金的显微组织

在Ａｌ－Ｔｉ－Ｎｂ－８Ｍｎ四元系邻近Ｌ１２型Ａｌ３Ｔｉ－８Ｍｎ成份区合金中，随Ｎｂ含量变化，其显微组织发生明显变化。通过对不同合金的微观组织的考察，进一步确认了在Ａｌ６７Ｍｎ８Ｔｉ２５基金中加Ｎｂ并相应调整Ａｌ和Ｔｉ含量可形成ＤＯ２２型Ａｌ３（Ｔｉ，Ｎｂ），Ｌ１０型ＴｉＡｌ和Ｇａ２Ｈｆ型Ａｌ２Ｔｉ３种类型的第二相。本文列举了Ａｌ６７Ｍｎ８ｔＩ２３Ｎｂ２，Ａｌ６５Ｍｎ８Ｔｉ２６－５Ｎｂ０．５，Ａｌ５

Microstructures of Multiphase Al_3Ti-8Mn-Based Alloys

The microstructures of the alloys near the Al3Ti-8Mn composition region of the Al-Ti-Nb-8Mn quaternary system changewith variation of the Nb content. The microstructures have been investigated using optical microscopy, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). It is determined that in Al67Mn8Ti22-based alloys modified with Nb the secondphases can be DO22 Al3 (Ti,Nb), L10 TiAl or Ga2Hf type of Al2Ti. The microstructures of four typical experimental alloys, A67,Mn8Ti23Nb2, Al59Mn8Ti30Nb3, Al65Mn8Ti26.5Nb0.5 and Al65Mn8Ti23Nb4,are presented in this paper. The second phase Al3 (Ti, Nb)particles con be dispersed blocky or dendritic,the L10 TiAl particles are ripple-like or needle-like, and Ll10 TiAl arrays alternately withL12 matrix. The netty Al2Ti phase is plate-like under TEM and distributes across the L13 matrix.