Rapid oxidation and its effects on mechanical properties of V–Ti–Cr–Si type alloys

A series of V–Ti–Cr–Si type alloys were prepared to develop oxidation-proof vanadium alloys. The alloys of V–4Ti–4Cr–(0-0.5)Si–(0-0.5)Al–(0-0.5)Y were selected for the oxidation experiment. Rapid oxidation experiments in air were carried out at 300°C, 500°C and 700°C for 3.6 ks. After oxidation, measurement of weight gain and Vickers micro hardness test were conducted. The weight gain became appreciable at 700°C oxidation treatment and the more Si, Al and Y added, the larger the weight gain of the specimen was in the present condition. The result of tensile test at room temperature showed that elongation decreased with the oxidation temperature increased. After oxidation at 700°C, each specimen ruptured in elastic deformation region. The specimens were examined by scanning electron microscopy (SEM) in order to characterize the oxide layer and fracture surface. It indicated that there were three distinct regions from the surface of the specimen on the cross-sectional area, which were oxide layer, cleavage fracture zone and ductile rupture zone. The thickness of the oxide layer after 700°C oxidation increased with further addition of Si, Al and Y.