Evolution of phases in Al55Ni30Pd15 alloy at temperatures up to 600 °C

• Phases (Ni,Pd)Al and Al3(NiPd)2 were identified in Al55Ni30Pd15 alloy.
• Two isostructural (Ni,Pd)Al phases were formed during annealing at 600 °C.
• Lattice parameters of Al3(NiPd)2 were found to decrease with increasing temperature.

The originally as-cast Al55Ni30Pd15 alloy was investigated during continuous heating from room temperature to 600 °C and after annealing at 600 °C for respective 455, 2650, and 4050 h. In the investigation the synchrotron X-ray diffraction and the high-resolution scanning electron microscopy inclusive of the energy-dispersive X-ray spectroscopy were used. In all the investigated conditions β-(Ni,Pd)Al (Pm3m) and Al3(NiPd)2 (P3m1) phases were identified. After 2650 h of annealing the former phase was found to be separated into two isostructural modifications differing from one another in Pd- and Ni-contents. The annealing for 455 h contributed to the decrease of lattice parameters in the Al3NiPd phase compared to the original as-cast condition.