Effects of sintering condition and heat treatment on the mechanical properties of W-Mo-Ni-Fe sintered alloys

The mechanical properites of 90W4Mo4Ni2Fe sintered alloys were studied. The specimen which was not sufficiently reduced in the heating process before the rapid densification which occurred by the liquid generation (above 1453 deg C), showed inferior mechanical properties even if the sintering time was prolonged. It was considered that the deterioration of the mechanical properties was caused by the lowering of the boundary strength owing to the segregation of oxygen. The mechanical properties of the specimen which was sufficiently reduced and sintered were much improved by the heat treatment. For example, mechanical properties of the specimen heated up at about 6.3 deg C/min, sintered at 1500 deg C for 90 min in H and then quenched after keeping for 60 min at 1000 deg C in N were as follows; the tensile strength is 96.7 kgf/mm exp 2 and the elongation is 20.4%. 7 ref.--AA