Preparation of Mo-Re powder and alloy samples doped with different second phases

Molybdenum rhenium (Mo–Re) composite powders with different second phases and high-density Mo–Re alloys was prepared by a solid-solid mixing and hydrogen pressureless sintering process. The ZrO2, ZrC, and Ti3AlC2 were selected as the second phase. The morphology and phase composition of the composite powders, as well as the microstructure and properties of the Mo–Re alloys, were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the average particle size of the Mo–Re composite powder after hydrogen reduction was 640 nm with an oxygen content of only 0.012%, and the Mo and Re elements form a rich Mo solid solution through solid solution formation.. The average particle sizes of ZrO2 and ZrC ceramic reinforced Mo–Re composite powders are 360 nm and 310 nm, respectively. After the addition of Ti3AlC2 particles, a large amount of free ultrafine nano powder was adsorbed around the layered structure, and the rest was Mo–Re composite powder of conventional size. The average grain size of sintered pure Mo–Re alloy was 35.73 μm, and the average grain size was obviously smaller than that of Mo-Re after adding ZrO2, ZrC and Ti3AlC2 particles, and the average grain sizes were 19.76 μm, 15.68 μm and 29.57 μm respectively. Fine ZrO2 particles in the sintered state were dispersed in the grain, which effectively hindered the migration of Mo-Re grain boundaries, reduced the driving force of grain growth and inhibited grain growth. ZrC particles reacted with oxygen during high temperature sintering to generate ZrO2 particles, which purified grain boundaries. Ti3AlC2 particles were sintered in high temperature reducing atmosphere for a long time, and topological reaction occurred, and layered AlTi3 and Ti5O9 were generated in situ to enhance the properties of the alloy.