Effect of Al2O3 content and swaging on microstructure and mechanical properties of Al2O3/W alloys

Al2O3-reinfored tungsten alloys were fabricated by powder metallurgy method and hot swaging technology. The investigation was made on the microstructure, relative density, nano-hardness and fracture toughness (K-IC) of the sintered and swaged Al2O3/W alloys. The swaging process and addition of Al2O3 are beneficial to comprehensive properties of the sintered and swaged alloys. After swaging, the Al2O3/W alloys can achieve the full density. According to the nano-indentation test and three-point bend test, the swaged W-0.25 wt% Al2O3 alloy possesses the highest hardness of 7.02 GPa, the greatest modulus of 435.09 GPa and the maximum fracture toughness of 21 MPa.m(1/2). The observation of fracture morphology shows that the recrystallization behavior and grain growth occur above 1400 degrees C in the swaged pure W alloy, which leads to recrystallization brittleness. At the same time, the microstructure of the swaged W-0.25 wt% Al2O3 alloy does not change apparently.