Selective Electron Beam Melting of TiAl Alloy: Metallurgical Defects, Tensile Property, and Determination of Process Window

Abstract

Selective electron beam melting (SEBM) is a promising method to manufacture complex titanium aluminide (TiAl) alloy parts. Herein, the effects of beam current, scanning speed and energy density on surface appearance, porosity, and Al loss of Ti–47Al–2Cr–2Nb alloy samples fabricated by SEBM are investigated systematically. The porosity decreased initially and then increased, and Al loss increased gradually with an increase in beam current. The porosity increased continuously and the Al loss decreased gradually with an increase in scanning velocity. The tensile strength decreased when the porosity of SEBM‐produced TiAl alloy increased. The processing window for Ti–47Al–2Cr–2Nb alloy fabricated by SEBM is determined from the energy density and scanning speed, and the formation mechanisms of small pores and B2 phase precipitation around partially melted powder are explained in detail. The findings provide a valuable reference for fabricating Ti–47Al–2Cr–2Nb alloy by SEBM with a desired surface appearance, porosity and Al loss.