Effects of metal carbides as additives on combustion synthesis of Ti3(Al,Sn)C2 solid solutions

Abstract

Formation of the Ti3(Al,Sn)C2 solid solutions with a broad substitutional range was investigated by combustion synthesis from elemental powder compacts with Al4C3 and TiC additions. High combustion temperatures of 1590–1700 °C and rapid flame-front speeds of 14.2–18.8 mm/s were measured for the Al4C3-adopted samples. Due to the dilution effect of TiC, the combustion temperature and velocity were significantly reduced for the TiC-added samples and approximated to 1220–1280 °C and 7.1–9.6 mm/s, respectively. The XRD analysis indicated that Ti3(Al1–xSnx)C2 solid solutions with x = 0.2, 0.4, and 0.6 were produced from the Al4C3-adopted samples. Further increase of Sn to x = 0.8 led to the formation of a large amount of Ti2SnC and TiC. Because of the low reaction temperature for the TiC-based reaction scheme, the effective substitution of Sn for Al in Ti3(Al1–ySny)C2 was only achieved at y = 0.2 and 0.4. Incomplete phase formation at y = 0.6 and 0.8 yielded Sn-lean Ti3(Al,Sn)C2 along with Ti2SnC, TiC, and free Sn. The as-synthesized Ti3(Al,Sn)C2 grains were formed into the shape of platelets and most of them were closely stacked into a laminated microstructure.