Influence of boron nitride on reinforcement to improve high temperature oxidation resistance of titanium

Influence of boron nitride (BN) addition in commercially pure titanium (Cp-Ti) was characterized for their microstructural variation, hardness, and oxidation kinetics. Feedstock powders, Cp-Ti with 3 wt% BN (3BN) and 6 wt% BN (6BN), were prepared by roller mill followed by additive manufacturing using laser engineered net shaping (LENS T). Rate of oxidation was measured from thermogravimetric analysis (TGA) at 1000 degrees C for 50 h. Average instantaneous parabolic constants (kp) for Cp-Ti, 3BN, and 6BN were 41.2 +/- 12.0, 28.6 +/- 2.8, and 18.2 +/- 9.2 mg(2)/(cm(4) h), respectively. Cp-Ti displayed acicular alpha-Ti microstructure. After TGA, large equiaxed grains along with TiO2 formation at the grain boundaries were observed, which increased the hardness. With BN addition, plate-like TiN and needle-like TiB secondary phases were also observed. Hardness for Cp-Ti, 3BN, and 6BN were 256.9 +/- 7.7, 424.0 +/- 33.6, and 548.3 +/- 49.7 HV0.2, respectively. Overall, a small addition of BN was effective in improving the oxidation resistance of Cp-Ti.