Densification change due to effect of liquid phase sintering on 90 W–7Ni–3Fe alloy at different pressing loads

Abstract

The current investigation explores how compaction under different loads affects the sintering performance of the 90 W-7Ni-3Fe alloy. Four different loads were used to compact Tungsten, Nickel, and Iron powder to make a cylindrical green pellet of 90 W-7Ni-3Fe alloy, namely 150 MPa, 250 MPa, 350 MPa, and 450 MPa. After compaction, the green pellets were sintered in liquid phase at a temperature of 1500 °C in a conventional furnace under a hydrogen gas environment to investigate their effect on densification and dimensional shrinkage of the sintered compact. It was found that the sintered density increased as the compaction load increased, resulting in enhanced densification. Due to the use of hydrogen gas in liquid state sintering, high densification was achieved by the compacts since it rapidly reduced the oxides and the porosity of the pellet. Compact pressed under a 450 MPa load and sintered attained 98.44 % density, which is nearly equal to the industrially prepared 90 W-7Ni-3Fe compact. The radial shrinkage of cylindrical compacts has been observed to be greater in relation to the axial shrinkage. As the compaction load increases, the shrinkage of the sintered pellet decreases.