Designed Experiments for Optimized Mechanical Properties in Cast and PM TiAl-based Alloys

摘要

Two processing routes were compared in the present work using the well-known TH46. 5-48)Al-2Cr-2Nb (at%) alloy,i. e. centrifugal casting and prealloyed powder metallurgy. Systematic heat treatment studies were performed on cast and PM parts for in-depth microstructural investigations. An extensive test matrix was carried out to investigate the effects of Al stoichiometry and microstructure on tensile and creep properties. For this purpose,Taguchi-type designed experiments were used to determine the predominant structural factors that intervene in key properties such as yield strength,tensile ductility,primary creep strain,secondary creep rate and tertiary creep stage. For PM processing,heat treatment parameters were used to quantitatively analyze the microstructure. Tensile properties were comprehensively related to the microstructural parameters of the PM alloy. For both cast and PM processing routes,analysis of the Taguchi calculations using the experimental data is critically discussed in the paper.thus leading to the interpretation of the major trends and of the underlying deformation mechanisms. Finally,an attempt was made to assess the microstructural optimization for an adequate balance in tensile and creep properties.