Microstructure and Mechanical Properties of TiB₂/Al-Si Composites Fabricated by Electron Beam Rapid Manufacture

Abstract

Bulky sample was fabricated by electron beam rapid manufacture (EBRM) technology, in which Ф1.6 mm wire of in-situ TiB2/Al-Si compositeswas selected as deposition metal, following byT6 heat treatment. The microstructure and mechanical properties of the bulky sample before and afterheat treatment were analyzed. Experimental results showed that the microstructure parallel to the weld was similar to that perpendicular to the weld. The microstructure of the as-deposited sample consisted of columnar and equiaxed grains, in which siliconwas distributed along the grain boundary and the grain size was about 30 μm. Besides, some TiB2 particles converged at the grain boundary. After T6 heat treatment, the average grain size of the sample increasedobviously.The average hardness of the sample was increased to 114.65 HV from 46.55 HV, an increase of 146%. The tensile strength of the sample increased to 326.66MPafrom 143.97 MPa, but the elongationdecreased compared with that of the as-deposited state. The tensile test showed that the mechanical properties of TiB2/Al-Si composites formed by electron beam rapid manufacture were isotropic before and after heat treatment.