Experimental Study on Al-La Alloy Powder Suitable for Trace Addition in Cp-Ti Manufactured by SLM for Microstructure-Property Synergistic Control

Abstract

Aiming at the microstructure control of the commercially pure titanium (CP-Ti) manufactured by selective laser melting (SLM), an Al-50 %La alloy was selected and prepared in a vacuum medium-frequency induction furnace to be served as the research subject. The geometric characteristics of the Al-50 %La alloy powders prepared by the two different methods of mechanical pulverization and gas atomization were studied by comparison. The results showed that the Al-49.09 %La master alloy was obtained and the only intermediate phase containing La in the experimental alloy was Al11La3. From the perspectives of chemical composition, phase composition and ensuring effective addition of rare earth, the experimental alloy of Al-49.09 %La is suitable for preparing the trace additives used for the CP-Ti manufactured by SLM. Compared with the Al-La alloy powders prepared by the gas atomization method, although those prepared by the mechanical pulverization method had irregular shapes, the particle size was relatively smaller. The sub-micron level powders were obtained and the proportion of the powders with an equivalent particle size of less than 1 μm accounted for 4.38%. Considering the characteristics of the micro melt pools formed in SLM process, the small amount of the Al-La alloy sub-micron powders prepared by the mechanical pulverization can be used as the trace additives for microstructure control of the CP-Ti manufactured by SLM.

Keywords: Al-La alloy, SLM, CP-Ti, Trace addition, Powder particle size