Microstructure and high temperature compressive properties of Nb-based alloys fabricated by plasma arc-induction hybrid melting

A new melting system called plasma arc-induction hybrid melting technology was designed in this work to fabricate Nb-based alloys, which combines the advantages of plasma arc melting and levitation melting. The ternary alloy Nb-16Si-22Ti alloy ingot prepared by the new method was found to have a high level of chemical homogeneity with the difference of <0.5 at% in the concentration distribution. Three alloys C103, C109 and M532, which are the widely used alloy grades in industry, are chosen as base. Then, 16%Si and 22%Ti was added in the three base alloys and new alloys BC103, BC109 and BM532 were obtained to study the effects of Si and Ti addition on the microstructure and mechanical properties of Nb-based alloys. Among them, alloy Nb-16Si-22Ti-5Mo-2Cr-2Al-2Hf (BM532) was found to have the best high temperature compressive properties, which was used as base and W element was added as a replacer of Hf by 0, 1, 2 at% to further improve the high temperature mechanical strength of the alloy. The results indicated that alloy Nb-16Si-14Ti-5Mo-2Cr-2Al-1W has the best high temperature compressive properties, with a compressive strength of 1034 MPa at 1200 °C and 725 MPa at 1500 °C.