Structure and Phase Formation in Ni + Al Powder Mixture Enclosed in a Steel Cartridge during Hot Gas Extrusion

Stages of structure/phase formation in Ni + Al powder mixture enclosed in a steel cartridge in the course of hot gas extrusion (HGE) were studied. It was shown that the formation of target NiAl phase is preceded by the appearance of NiAl 3 , Ni 2 Al 3 , and Ni 3 Al phases. It was determined that the phase composition is formed prior to the onset of plastic deformation and retains constant in the course of extrusion process; meanwhile, the structure undergoes the changes, its grains are deformed, taking an elongated shape. It was found that HGE is characterized by a redistribution of elements. It can be assumed that to increase the target phase yield, it is necessary to compensate or eliminate the redistribution of elements.