Reducing the sintering temperature of tungsten alloys with introducing of new W-Ni-Si compositions: evaluation of microstructure and mechanical properties Bewertung des Gefüges und der mechanischen Eigenschaften durch Senkung der Sintertemperatur von Wolframlegierungen durch Einführung neuer W-Ni-Si-Zusammensetzungen

Abstract

The high sintering temperature of tungsten heavy alloys is one of the problems in the production of this alloy. In this research, with the aim of reducing the sintering temperature, W-(10-x) Ni-x Si alloy with different amounts of silicon (x = 0.8 wt.%, 1.2 wt.% and 1.6 wt.%) were designed. These alloys were pressed at 1050 °C, 1100 °C and 1150 °C under a pressure of 30 MPa. The microstructure, composition, density and compressive properties of the samples were examined. The highest relative density was about 99.52% for W-8.8Ni-1.2Si alloys at 1150 °C. By increasing the silicon, the density and tungsten particle size initially increased and then decreased. Intermetallic and unwanted compounds were observed in the microstructure of the W-8.4Ni-1.6Si alloy. At 1100 °C, the compressive yield strength decreased with an increase in silicon, but at 1150 °C, it did not change significantly. In both temperatures, the compressive strain decreased with increasing silicon. At 1100 °C, the compressive yield strength of alloys with 0.8 wt. %, 1.2 wt. % and 1.6 wt. % silicon were about 1303 MPa, 1231 MPa, and 670 MPa, respectively. The results showed that W-Ni-Si alloys had higher density and compressive yield strength than common W-Ni-Fe alloys, although the sintering temperature was lower.