Effects of Ti, Al and Hf on niobium silcides formation in the Nb-Si in situ composites

The effects of alloying elements Ti, Al and Hf on niobium silicides formation in the Nb-Si in situ composites have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The binary, ternary and multicomponent alloys have been fabricated by vacuum non-consumable arc melting method. The results show that Ti tends to stabilize Nb3Si phase, while Al promotes the direct formation of β-Nb5Si3 phase with a tetrahedral D8 m structure. Exceptionally, it seems that Hf is beneficial to the formation of γ-Nb5Si3 phase with a hexangular D88 structure. For the multicomponent Nb-Si in situ composites, the cooperative effects of different elements on niobium silicides formation basically maintain the character of ternary system.