Effect of alloyed Ti:Zr ratio on phase stability of Al66Mn9(Ti,Zr)(25) intermetallic compounds

Abstract

The tetragonal Al-3(Ti1-xZrx) phase is transformed by the addition of 9% Mn to the cubic L1(2)-type Al66Mn9(Ti1-xZrx)(25) with a small amount of second phases such as Al8Mn5 and Al2Zr still existing in the as-cast condition. Second phases disappear when intermetallic compounds are homogenized at 1000 degrees C for 24 h, and alloys are of the monolithic L1(2) phase with compositional variations still existent. The combined addition of Ti and Zr is found to reduce the hardness of intermetallic alloys compared to the addition of Ti or Zr alone. The Al66Mn9(Ti, Zr)(25) phase is found to be structurally stable but compositionally unstable.