Ductility Improvement by Microstructural Control on Multiphase Intermetallic Alloys Using Phase

已经有几个例子，其中在由具有不同有序晶体结构的金属间相组成的显微组织中的控制是成功的，所述金属间相在多组分合金系统中是相邻的，以在室温下提供可观的拉伸延展性。然而，在这些情况下，似乎很难同时获得足够的高温强度，这是由于在高温下精细微观结构的不稳定性。本工作旨在通过在足够高的温度下相分解来开发多相金属间合金，使得所产生的微观结构在超过1273 K的温度下是稳定的。选择Mo系作为合金系是因为似乎存在一个成分区域，在该区域中B2相分解成L1_2Ni_3Al和α-Mo末端固溶体α（Mo），通过差热分析和显微结构观察进行相图评估，然后通过以下方法制造选定的合金：电弧熔炼。结果表明，某些合金，如Ni-22at%Al-8at%Mo合金，具有优良的高温强度和一定的室温塑性。

There have been several examples in which the control in the microstructure consisting of intermetallic phases with different ordered crystal structure which are neighboring in the multi-component alloy systems was successful to provide appreciable tensile ductility at room temperature. However it seems in those cases to be difficult to achieve enough high temperature strength at the same time due to the instability of a fine microstructure at elevated temperatures.The present work is designed to develop multi-phase intermetallic alloys through a phase decomposition at a high enough temperature so that a microstructure produced would be stable at temperatures over 1273 K.The Ni-Al-Mo system was chosen as an alloy system because there seems to be a compositional region in which the B2 phase decomposes into the Ll_2 Ni_3Al and the alpha-Mo terminal solid solution, alpha(Mo), at around 1573 K.Phase diagram evaluation by differential thermal analysis and microstructural observation is followed by fabrication of selected alloys by arc-melting. It is then shown that some alloys, typically aNi-22at%Al-8at%Mo alloy, exhibits an excellent high temperature strength with some room temperature ductility.