Thermal stability of high-temperature Ni–Mn–Ga alloys

The thermal stability of high-temperature Ni–Mn–Ga alloys by ageing at temperatures in the range 620–770 K was studied. The results indicate that increasing the e/a ratio by substitution of Ga with Mn, keeping Ni close to stoichiometry, results in very stable alloys under ageing. However, increasing the e/a ratio by increasing the Ni content, either by substitution of Ga or reducing the Mn content, leads to faster decomposition.