Study on Evolution of Ti-containing Intermetallic Compounds in Alloy 2618-Ti during Homogenization

Dispersive Al3Ti particles introduced into alloy 2618-Ti are enclosed gradually by ternary Al18Mg3Ti2 phase during homogenization, which can be described as a "peritectic reaction". This reaction is sensitive to homogenization temperature and time within 24 h but not so -sensitive to homogenization time after 24 h because of its special growth pattern. The evolution of the intermetallic compounds during homogenization process of alloy 2618-Ti is further confirmed by means of diffusion couple of (Al-25Mg)/(Al-10Ti). After homogenization, much Al3Ti particles coexist with Al18Mg3Ti2 which depends on the composition of Al-Mg-Ti system and only a few single Al18Mg3Ti2 appear. The occurrence of single Al18Mg3Ti2 phase, within which Al3Ti disappears, can be attributed to the local fluctuation of alloy compositions.