Study on the silicide phase control and room temperature mechanical properties of Nb-Si-Ti based alloys via B and Mg-microalloying

Abstract

The Nb-16Si-20Ti-4Cr-1.5Al-4Hf-4Zr-1Ta-xB (x=0, 2, 4)-yMg (y=0, 0.2, 0.4) alloys were prepared by non-consumable arc melting. The effects of B and Mg addition on the microstructure and room temperature fracture toughness have been investigated. The results reveal that when the content of B element reached 4 at.%, the intermediate metastable phase Nb3Si was precipitated in Nb-Si based alloys. The cooperation of B and Mg synergistically enhances the room temperature fracture toughness of Nb-Si based alloy. B and Mg element causes the eutectic point of Nb-Si based alloy to shift to the right. The 2B-0.4Mg alloy shows the best fracture toughness, and its KQ value is 14.41 MPa·m 1/2, which increased by 34% compared to the matrix alloy. Crack deflection and secondary cracking increase the room-temperature fracture toughness of Nb-Si-based alloys.