Tungsten Heavy Alloys: Sintering Temperature’s the Key to Density, Strength, and Ductility

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 density sintering temperature
Tungsten Heavy Alloy W90NiFe Density Change

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 W90NiFe Strength Change
Tungsten Heavy Alloy W90NiFe Strength Change


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.

tungsten heavy alloy ductility sintering temperature
Tungsten Heavy Alloy Ductility Change