ORIENTATION AND TEMPERATURE-DEPENDENCE OF YIELD STRESS AND SLIP GEOMETRY OF TI3AL AND TI3AL-V SINGLE-CRYSTALS

Single crystals of binary Ti3Al and ternary Ti3Al-V alloys with the D0(19) structure were deformed in compression at 20-900-degrees-C. Slip systems of the {1010BAR}[1210BAR]-type and the {1121BAR}[1126BAR]-type were observed in these alloys throughout the entire temperature range depending on orientation, but the {1121BAR}[1126BAR]-slip was limited to orientations near [0001]. The basal (0001)[1210BAR]-slip was also activated in quenched Ti3Al. The CRSS for the {1010BAR}[1210BAR]-slip in the binary and ternary alloys decreases monotonically with increasing temperature. In the ternary alloy the CRSS for the {1010BAR}[1210BAR]-slip shows a violation of Schmid's law, while the binary alloy obeys the CRSS law. When Ti3Al is deformed by {1121BAR}[1126BAR]-slip the CRSS for the slip exhibits an anomalous peak in the temperature-CRSS curve but the addition of vanadium suppresses the extent of the anomalous strengthening.