Abstract: The relationship between mechanical properties and nickel to iron ratios of W-Ni-Fe tungsten heavy alloys (WHAs) heat treated by solid-solution and quenching was studied. It was found that under solid-solution and quenching state the best nickel to iron ratio moved from 7/3 to 9/1. And it was also found that the tensile strength and ductility of resolutionized/quenched WHAs have the same changing tendency with increasing nickel to iron ratios, namely the mechanical properties increased with increasing nickel to iron ratios, reaching the maximum when the ratio approached to 9/1, and then decreased as the ratios getting higher. X ray diffraction and TEM analysis showed that there were brittle β(WNi₄) phase precipitated in slow-cooled after sintering WHAs, and that the solid-solution and quenching heat treatment was effective to inhibit the precipitation of WNi₄.