Microstructure and deformation behavior of Ti-(43-54)Al-xMn-yNb(x=0,3,4,y=0,4) alloys－Deformation and micro-fracture behavior

摘要

A study was carried out to investigate the effect ofMn on the deformation and micro-fracture behavior in Ti-(43-54)Al-xMn-yNb(x=O, 3, 4, y=O, 4) alloys. No deformation twinwas observed, while faulted dipoles were promoted during roomtemperature deformation of Ti_(49)Al_(51) alloy. However, in(Ti_(49)Al_(51))_(97)Mn_3 alloy, a certain deformation twinswere observed. In addition to deformation twins and ordinarydislocations, superlattice dislocations and the faulted dipoles wereobserved in both (Ti_(53)Al_(47))_(97)Mn_3 and(Ti_(55)Al_(45))_(97)Mn_3. However, there was no remarkabledifference in the operative deformation mode between(Ti_(53)Al_(47))_(97)Mn_3 and (Ti_(55)Al_(45))_(97)Mn_3alloy. For both Ti53A147 and (Ti_(53)Al_(47))_(97)Mn_3, somerecrystallized grains were found after deformation by 35%compressive strain at both 700 deg C and 900 deg C. Therecrystallized grains of (Ti_(53)Al_(47))_(97)Mn_3 alloy weresmaller than those of Ti_(53)Al_77 alloy. In-situ TEM experimentwas carried out to observe the effect of Mn on the fracturebehavior in lamellar microstructure. In(Ti_(53)Al_(47))_(97)Mn_3 alloy, the fracture planes weredetermined as (1ll) and (001) planes and the main crack waspropagated continuously across the lamellae. Also, in-situ SEMexperiment was carried out to observe the effect of the lamellarorientation against the loading axis.