Effect of parent phase ageing on CuZnAl shape memory alloys with Mn and Zr addition

A high-working-temperature CuAlMnZr shape memory alloy

“…A stable forward-reverse thermoelastic martensitic transformation takes place between 100 and 275 • C after the first thermal cycle. The shape memory ratio is maintained at a high value of 97.2% when the alloy is aged at 150 • C for 100 h. This may also be due to the addition of Mn, which may increase the binding force between the constituent atoms, leading to increased activation energy for diffusion and decreased diffusion rate of the atoms for re-ordering [18].…”

“…This reduces the amount of the parent phase available for martensitic transformation. Consequently, shape memory capacity of the alloy decreases accordingly [18]. For the Cu-Al-Ni alloy [19], the eutectoid decomposition (␤ → ␣ + ␥ 1 ) occurs when heated to 550 • C. Only 10% of the ␤ phase remained untransformed, resulting in a significantly decreased mass fraction of thermoelastic martensite.…”

Macroscopic shape change of Cu13Zn15Al shape memory alloy on successive heating

“…The distance between (1 2 2) M and (2 02) M , as well as the distance between (1 2 1 0) M and (2 0 10) M , decreases during martensite stabilization process, a transformation from M 18R to N l 8R occurs. Such a transformation is a consequence of the order-disorder atomic diffusion process [13][14][15]. The basal plane of the ordered thermoelastic martensite cannot be closely packed into a regular hexagon as the ordered Cu, Zn and Al atoms have different radii.…”

Prediction of Thermodynamic Equilibrium Temperature of Cu-Based Shape-Memory Smart Materials

“…The addition of Mn may increase the binding force between the constituent atoms. [30] The substitution of Mn with Al is known to reduce the fault probability to increase the stacking fault energy. Consequently, it can be expected that in an alloy in which Al has been replaced by Mn there will be an additional decrease in the distance between the partial dislocations with respect to the alloys without Mn having been added.…”

“…[31] It is suggested that the addition of Mn inhibits the activities of vacancies by lowering their diffusion rate in both the martensite stabilization and the parent-phase stabilization processes. [30] A content of Mn up to 12 wt pct may improve the ductility, the formation of the c 2 phase, and the machining properties. [17] Figure 9 shows the effect of the less soluble element Ti on T 0 temperature in Cu-based SMAs.…”