Mo diffusion and In-situ formation of reinforcement in spark plasma sintering of powder mixed Ti-10Mo-1.5B4C composite at different temperatures and holding time

Titanium boride and titanium carbide are the most important ceramic particles to reinforce titanium-molybdenum alloys. If an external reinforcement with an exothermic reaction causes the production of those reinforcements, the heat of reaction can promote the diffusion of molybdenum in the Matrix.

In this research, Ti–10 wt.% Mo–1.5 wt.% B4C composite samples was consolidated in a SPS machine following cold uniaxial precompaction by applying maximum 10 MPa and then SPSed in vacuum below 1 Pa at 1150, 1300 and 1450°C with 50°C/min heating rate under 20 MPa pressure. Subsequently at each sintering temperature the applied pressure was increased to 50 MPa and process continued for 5 and 10 min. Microstructural changes, physical and mechanical properties as well as phase analysis of produced composites were evaluated.

Totally, with rising sintering temperature and time, the density increases. Only at 1450°C for 10 min, a slight decrease in density was observed. Similarly, the mechanical properties improved. Actually, increasing sintering temperature influences the progress of the titanium-boron carbide reaction and the decreasing porosity greater than time. Here, not only increasing sintering temperature and time but also the heat of exothermic reaction encourages the diffusion of molybdenum to matrix and lead to better homogenization, consequently.  Under similar elaborated arrangement, also achieving improved mechanical properties is more accessible.