Microstructure and mechanical properties of Ti-TiBw-x%Cu composites by powder metallurgy using atomized Ti-TiBw powder as raw materials

Titanium matrix composites (TMCs) reinforced with titanium boride whisker (TiBw) prepared by conventional smelting or powder metallurgy via in-situ techniques are inevitable to cause TiBw coarsening by high-temperature thermal history, which feasibly leads to stress concentration and results in seriously inverse relationship between strength and toughness. This paper developed a novel strategy using Ti-TiBw composite powder as raw powder which is produced by the plasma rotating electrode atomization method (PREP), to control TiBw to nanoscale size by taking advantage of the rapid cooling rate of PREP. On this basis, the fast eutectic element Cu was proposed as alloying element and introduced into Ti-TiBw composite system using powder metallurgy, to investigate the influence rules of Cu content on TiBw scale characteristic parameters (diameter and aspect ratio, etc.) as well as the microstructure and mechanical properties of Ti-TiBw composites. The hardness of the specimen was increased by 61.9%, while its tensile strength and yield strength were increased to 823 ± 12 MPa and 602 ± 11 MPa, respectively. Its elongation retained the same level at 10.8 ± 1.9% as that of Ti-TiBw composites.