A Comparative Study of the Creep Resistance Improvement between the Interstitial Alloying Elements and Different Heat Treatments for TiAl Alloy

초록

It is well known that TiAl alloy with a fully lamellar structure shows the highest creep resistance. In the fully lamellar structure, there exist abundant lamellar interfaces and the microstructure has an important role on the creep resistance. Recently, some efforts to improve the creep resistance of lamellar TiAl alloy have been reported. With decreasing lamellar spacing and an interstitial alloying(carbon addition) effect, the creep resistance of lamellar TiAl would be improved. However, the microstructure can be changed by carbon addition. The primary alloy has a composition of Ti-46.6Al-1.4Mn-2Mo (at.%), which was made by EPM method. Primary test alloys have three different lamellar spacing with different cooling process and three different amounts of carbon were added to the normal alloy (0.15, 0.3 and 0.6 at.%). To compare with creep resistance, constant tensile stress creep tests were conducted at the condition of 800oC ~900oC/150MPa. In this investigation, the effective method to improve the creep resistance of lamellar TiAl will be discussed with different lamellar spacing and carbon contents.