Effect of cyclic heat treatment on impact toughness of 93W–5Ni–2Fe tungsten heavy alloy

The 93W‒5Ni‒2Fe tungsten heavy alloys (WHAs) were prepared by powder metallurgy method, and then subjected to the cyclic vacuum heat treatment at 1200 ℃ and the oil quenching rapid cooling. The impact toughness of WHAs treated by the same heat treatment was studied by the impact toughness test and the fracture morphology analysis. The results show that, with the increase in the cycle number of heat treatment, the impact toughness of WHAs increases gradually, and the impact toughness reaches 115 J·cm⁻² after the fourth cycle heat treatment. However, the impact toughness of WHAs does not change significantly when the cycle number of heat treatment is further increased. The impact fracture of WHAs is mainly cleavage fracture of tungsten grains after the first cycle heat treatment, and then gradually transitions to the ductile fracture of the cohesive phase between tungsten grains.