Mechanical Properties and Wear Resistance of TiB2-Dispersed TiNi Pseudoelastic Alloy Fabricated by Spark and Resistance Sintering

Mixtures of Ti, Ni and TiB2, TiC or SiC powders were spark- and resistance-sintered to obtain TiB2, TiC or SiC dispersed TiNi pseudoelastic alloy. The alloys were annealed, solution treated and aged after the sintering. Nano-indentation tests, bending tests, and abrasion wear tests were carried out on these alloys. Nano-indentation tests showed that the TiNi alloy and ceramics-dispersed TiNi alloys exhibited larger displacement recovery than the reference materials such as steels and titanium alloy at the same indentation displacement. The solution treated and aged specimens exhibited larger displacement recovery than the annealed ones. Vickers hardness of the annealed alloys increased with increasing ceramics content, while relative density and bending strength decreased. TiB2 dispersed TiNi alloy has higher hardness than TiC dispersed TiNi alloy and larger bending strength than SiC added alloy. Abrasive wear resistance of TiB2 dispersed TiNi alloy was much larger than that of the steels and titanium alloys, which can be explained by the stress relaxation of pseudoelastic matrix surrounding ceramics particles. In addition, the TiNi alloys annealed after sintering exhibited better wear resistance than the solution treated and aged ones. The wear resistance of TiB2 dispersed TiNi alloy was larger than that of TiC dispersed TiNi alloy perhaps because of larger interfacial strength between TiB2 particles and TiNi matrix than that of TiC particles and TiNi matrix.