Most of them are basically similar to ordinary TiAl alloys, some are slightly different in composition, and their mechanical properties are not fundamentally different, and they all belong to the class of ordinary TiAl alloys. The high Nb TiAl alloys we studied belong to a class of high temperature and high performance TiAl alloys. The composition, strength and oxidation resistance of TiAl alloy are completely different from those of ordinary tial alloy, and the use temperature is increased by 60-100℃. Our research has promoted the development of high temperature and high performance TiAl alloys at home and abroad. The purpose is to improve the use temperature of ordinary TiAl alloy, that is, to improve the strength and oxidation resistance of ordinary TiAl alloy, so that high Nb TiAl alloy can be used at 840-900℃. The use temperature of high Nb TiAl alloy can reach 840-900℃, which shows the comparison between the tensile properties of high Nb Ti alloy and typical TiAl alloy. The tensile strength of high Nb Ti alloy is much higher than that of other TiAl alloys.
High Nb TiAl alloy has very good oxidation resistance. We pointed out for the first time in 1992 in the CORROSION magazine that niobium can significantly improve the oxidation resistance, and made a composition - oxidation diagram at four temperatures between 900℃ and 1200℃. It was pointed out that in Ti-Al-Nb ternary system, the alloy composition with the best oxidation resistance can be described as follows: Al = 55-64at %, Ti/Nb = 2-5. Their oxidation weight gain at 1100℃ and 1200℃ for 100 hours is 1-2mg/cm2 and 2-3mg/cm2 levels, respectively. And TiAl at 1100℃, 100 hours of weight gain has reached 120mg/cm2.
The alloy has excellent high temperature properties is a comparison of creep properties of high niobium titanium aluminum alloy and other TiAl alloys. The creep rate of high niobium titanium alloy is 1 ~ 2 orders lower than that of K5 alloy, the creep stress is 40-150MPa higher than that of alloy, and the service temperature is more than 60℃ higher than that of GKSS and K5 alloy.
