Tungsten heavy alloys offer numerous benefits across a wide range of industrial uses: high density, strength, and ductility; toughness and resistance to corrosion and oxidation; as well as excellent machinability. All these properties may be modulated by the choice of raw material composition; microstructure; working conditions; production methods; and especially sintering temperature.
Tungsten heavy alloy WNiFe with 90% tungsten, for example, displays noticeable performance differences when sintered at various temperatures between 1360°C and 1440°C, given consistent composition, material ratio, and microstructure.
Tungsten Heavy Alloy Density
Tungsten heavy alloys’ desired density depends largely on control of the proper sintering temperature. WNiFe alloy with 90% tungsten content reaches near-full density of 17.01 g/cm³ and a relative density of 99.2% at 1440°C. Tungsten particles dissolve more quickly with increasing temperatures between 1360°C and 1440°C until the ideal density is reached. Conversely, as the sintering temperature goes beyond 1440°C, density decreases commensurately as abnormally large grains form and pores become difficult to remove.
Tungsten Heavy Alloy Strength
Tungsten heavy alloys with 90% tungsten achieve maximum yield and tensile strength of 1,086.7 MPa and 1,920.5 MPa, respectively, at an optimal sintering temperature of 1440°C. Within a sintering temperature range of 1360°C to 1440°C, increasing temperature produces greater liquid bonding phases until full sintering at 1440°C, when the tungsten particles become firmly interconnected. Above this ideal temperature, however, the excessive growth of tungsten particles results in decreased dispersion of bonding phases and a reduction in the coordinated deformation capability of the particles. Moreover, due to a diminished interfacial area, the expulsion of pores becomes more difficult, causing the formation of voids between the tungsten particles. These factors collectively contribute to a degradation of the alloy’s mechanical properties.
Tungsten Heavy Alloy Ductility
Tungsten heavy alloys with 90% tungsten content display increasing elongation and cross-sectional shrinkage rates as the sintering temperature increases within the range of 1360°C to 1440°C. Above 1440°C, however, these rates decrease as the temperature rises. Specifically, when the sintering temperature climbs from 1420°C to 1440°C, elongation and cross-sectional shrinkage rates increase from 9.2% and 12.4% to 22.8% and 24.4%, respectively. Above 1460°C, both rates gradually decline, reaching 16.4% and 17.6% respectively.