| A study was carried out to investigate the effect of Mn on the deformation and micro-fracture behavior in Ti-(43-54)Al-xMn-yNb(x=0, 3, 4, y=0, 4) alloys. No deformation twin was observed, while faulted dipoles were promoted during room temperature defermation of Ti_(49)Al_(51) alloy. However, in (Ti_(49)Al_(51))_(97)Mn₃ alloy, a certain deformation twins were observed. In addition to deformation twins and ordinary dislocations, superlattice dislocations and the faulted dipoles were observed in both (Ti_(53)Al_(47))_(97)Mn₃ and (Ti_(55)Al_(45))_(97)Mn₃. However, there was no remarkable difference in the operative deformation mode between (Ti_(53)Al_(47))_(97)Mn₃ and (Ti_(55)Al_(45))_(97)Mn₃ alloy. For both Ti_(53)Al_(47) and (Ti_(53)Al_(47))_(97)Mn₃, some recrystallized grains were found after deformation by 35% compressive strain at both 700℃ and 900℃. The recrystallized grains of (Ti_(53)Al_(47))_(97)Mn₃ alloy were smaller than those of Ti_(53)Al_(47) alloy. In-situ TEM experiment was carried out to observe the effeet of Mn on the fracture behavior in lamellar microstructure. In (Ti_(53)Al_(47))_(97)Mn₃ alloy, the fracture planes were determined as (111) and (001) planes and the main crack was propagated continuously across the lamellae. Also, in-situ SEM experiment was carried out to observe the effect of the lamellar orientation against the loading axis. |
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