复相Al_3Ti-8Mn基合金的显微组织

Microstructures of Multiphase Al_3Ti-8Mn-Based Alloys

在Al－Ti-Nb-8Mn四元系邻近L12型Al3Ti－8Mn成份区域合金中，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基合金中加Nb并相应调整Al和Ti含量可形成DO22型Al3（Ti，Nb），L10型TiAll和Ga2Hf型Al2Ti3种类型的第二相。本文列举了Al67Mn8Ti23Nb2，Al65Mn8Ti26Nb0．5，A159Mn8Ti30Nb3和Al65Mn8Ti23Nb44种典型实验合金的显微组织特征。Al3（Ti，Nb）相的形貌可呈弥散点状、块状或枝晶相。L10TiAl相的金相和SEM组织为波纹状或针片状，其TEM形貌为与基体交替排列的条状。网纹状Al2Ti在TEM下则是薄片状，并交叉规则分布于L12基体中。

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.