Effects of Mn addition on microstructure and mechanical properties of (Al+x at.%Mn)(3)Ti intermetallic compounds prepared by mechanical alloying and spark plasma sintering

Abstract

Effects of Mn addition on microstructure, phase stability and mechanical properties of (Al + x at.%Mn)(3)Ti intermetallic compounds fabricated by mechanical alloying and spark plasma sintering were investigated. As-milled ternary powders consist of homogeneous distribution of fine crystallites in amorphous matrix. (Al + 0.08 Mn)(3)Ti showed the most stable thermal stability with average grain sizes of less than 60 and 100 nm after heat treatments at 900 and 1100 degreesC, respectively. The reduction of grain size down to nano-scale was not sufficent enough to increase the fracture toughness of trialuminide. Fracture toughness was also remained relatively constant and showed no significant dependence oil Mn concentration. Microhardness was generally increased with increasing Mn,In concentration and decreased with increasing heat treatment temperatures due to the grain size effects. The formation of L1(2), phase played a major role in increased fracture toughness and (Al + 0.08 Mn)(3)Ti showed the highest fracture toughness of 4.12 MPa m(1 2) with only L1(2) phase formation. (C) 2004 Elsevier Ltd. All rights reserved.