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)(5)Si-3 and Laves phase NbCr2. The ISM ingots exhibit the finest microstructure, while the VCAM ingot shows the coarsest microstructure. Refined at 1800 degrees C for 10 min, the VIM ingot with a 0.1% carbon addition shows the best room temperature toughness of 9.05 MPa m(1/2) on average, however, the highest strength at 1250 degrees 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. (C) 2010 Published by Elsevier B.V.