Solid-solution strengthening and high-temperature compressive strength of Nb-X alloys (X=Ta, V, Mo and W)

The effect of alloying on the solid solution strengthening and compressive strength of Nb-X (X = Ta, V, Mo and W) binary alloys was studied by Vickers hardness measurements at room temperature and compression tests at high te mperature up to 1873 K. The changes of lattice parameter caused by alloying were investigated by X-ray diffractometry. It is found that the solid solu tion strengthening in the binary alloys primarily depends on atomic size mi sfit. No apparent solid solution strengthening is observed in Nb-Ta binary alloys up to 1873 K. In V added alloys, the 0.2% flow stress increases with increasing V content below 1600 K, but solid solution strengthening disapp ears above 1600 K. In Mo or W added alloys, the 0.2% flow stress increases with increasing Mo or W content at temperatures ranging from room temperatu re to 1873 K. The ductility of Nb-X binary alloys decreases with increasing alloying content, but it is improved by increasing temperature. In the all oys with less than 20 mol%Mo, 10 mol%W and 10 mol%V, large compressive duct ility is recognized.