Powder Size Influence on Tensile Properties and Porosity for PM Ti_2AlNb Alloy Prepared by Hot Isostatic Pressing

Pre-alloyed powder of Ti₂AlNb alloy was prepared by electrode induction gas atomization method, and the powder was screened into five kinds of powder size distribution. Fully dense Ti₂AlNb alloy was prepared by powder metallurgy (PM) using hot isostatic pressing. The properties of pre-alloyed powder and PM Ti₂AlNb alloy were tested. Results show that mean grain size of PM Ti₂AlNb alloy is influenced by powder particle size, but particle size has no significant influence on tensile properties. Finer Ti₂AlNb powder has low Argon gas bubble ratio and high oxygen content, and poor flowability of finer powder increases the degree of difficulty during degassing. As a result, big pores (>?50 μm) are observed in PM Ti₂AlNb alloy prepared by finer powder and cause plasticity loss of tensile properties. In order to get a better comprehensive properties of PM Ti₂AlNb alloy, powder with an average size (~?100 μm) is suggested.