The liquid phase sintering of molybdenum with Ni and Cu additions

To increase the sintered density of Mo compacts, liquid phase sintering was employed by adding sintering aids, Ni and Cu. With 1.5 wt.% Ni sintered at 1370°C, the sintered density of Mo increased from 86.0 to 97.5%. When one-third of the Ni was replaced by Cu, the density was improved from 82.1 to 99.1% when sintered at 1300°C. Although copper has little solubility in molybdenum, and vice versa, it aids nickel in enhancing the sintering of molybdenum compact during heating in the solid state and during the liquid phase sintering. The dilatometer run indicated that the liquid formation temperature was lowered by 90°C. Better wetting on molybdenum particles was also observed. However, the Mo–Ni–Cu compact was still brittle due to the presence of brittle Mo–Ni compounds at the grain boundaries.