The effects of melting technologies on the microstructures and properties of Nb–16Si–22Ti–2Al–2Hf–17Cr alloy

This paper deals with the effects of vacuum non-consumable arc-melting (VCAM), vacuum induction melting (VIM) and induction skull melting (ISM) technologies on microstructures, mechanical properties and oxidation resistance of Nb–16Si–22Ti–2Al–2Hf–17Cr alloy. It is revealed that the microstructure of the Nb–16Si–22Ti–2Al–2Hf–17Cr alloy is composed of Nb solid solution (Nb,Ti)ss, silicide (Nb,Ti)5Si3 and Laves phase NbCr2. The ISM ingots exhibit the finest microstructure, while the VCAM ingot shows the coarsest microstructure. Refined at 1800 °C for 10 min, the VIM ingot with a 0.1% carbon addition shows the best room temperature toughness of 9.05 MPa m1/2 on average, however, the highest strength at 1250 °C was obtained on the ISM sample refined at technology parameters of 140 kw melting for 2 min + 160 kw melting for 3 min. In addition, oxidation resistance was greatly improved through the ISM technology compared with the VCAM technology.