Effect of beam power on the distribution statues of aligned TiBw and tensile behavior of trace boron-modified Ti6Al4V alloy produced by electron beam freeform fabrication

Abstract

Trace boron-modified Ti6Al4V walls were prepared by electron beam freeform fabrication (EBF3), and the role of beam power in the distribution statues of aligned TiB whiskers (TiBw) and tensile behavior was investigated. The results show that the studied beam power has a remarkable effect on the interval, number density and size of aligned TiBw, while the orientation remains unchanged. High-density and fine TiBw are achievable at a decreased beam power, and play a great role in the increment in strength. With an increase in the beam power, the interval between the aligned TiBw enlarges. It allows the vertical direction to tolerate a large amount of elongation before failure by reducing the crack-propagation rate, blunting and deflecting the cracks. Due to the presence of highly orientated TiBw, the transverse direction of all deposits suffers from a premature failure. This study provides a new route to obtain a desirable mechanical performance by tailoring the distribution statues of TiBw during additive manufacturing of such materials.