Evidence of dislocation dependent behaviour in superelastic Ti2448 (Ti-24Nb-4Zr-8Sn, wt%)

Understanding the Room Temperature Recovery Behavior in a Ti–24Nb–4Zr–8Sn Superelastic Alloy

“…As discussed earlier, this corresponds to a decrease in type III internal stresses. In an analogous but contrasting manner to the raising of σ SIM with mechanical cycling, a lowering of the internal stresses during an RT age stabilizes the β phase with respect to the α 00 phase, [15] leading to an increase in σ SIM and hysteresis width. Such a reduction in internal stress is not limited to the Ti-Nb system and could be applicable to RT aging in other superelastic systems, although further work would need to be undertaken to demonstrate this.…”

“…Nevertheless, previous work on this composition has similarly shown low sensitivity to ω iso even when heated to elevated temperatures. [15] The 2 mm plate was cold rolled to 0.5 mm final thickness, equivalent to a reduction ratio of 75%. Dog bone tensile samples with a gauge section of (0.5 Â 0.5) mm 2 were produced from the rolled material by electro-discharge machining.…”

“…[14] At these temperatures, the rearrangement of dislocation structures could help to accommodate their associated strain fields, in order to lower the overall energy, thus returning the microstructure to a condition more comparable to the unloaded specimen. [15] However, some recovery in σ SIM has also been seen after holding in ambient conditions and coincide with a decrease in the stable volume fraction of α 00 . [16] These effects have been shown to occur rapidly, with changes seen within an hour.…”