Design of novel NiSiAlY alloys in marine salt-spray environment: Part II. Al-Ni-Si-Y thermodynamic dataset

Abstract

The NiSiAlY material is a promising candidate to replace NiCrAlY, which can withstand the harsh salt-spray conditions in marine environment. To efficiently design novel NiSiAlY alloys, this work establishes a thermodynamic dataset of the Al-Ni-Si-Y quaternary system using the CALPHAD (CALculation of PHAse Diagrams) approach. We employ this database to calculate and predict the phase constitutions and solidification behaviors of different NiSiAlY alloys concerning the content variations of Al and Si. We have further proposed the selection of the NiSiAlY alloys for serving in marine salt-spray environment with three constraints: (i) outstanding mechanical property; (ii) good high-temperature anti-oxidation; (iii) excellent corrosion resistance. This results in a compositional range of the NiSiAlY alloys with 1 wt% <w(Si) < 5 wt%, 11 wt% <w(Al) < 20 wt% and w(Y) =1 wt%, which corresponds the L12+bcc_B2+Ni5Y ternary phase region at temperatures ranging from ∼500 to ∼1000 °C. Our predictions are validated by key experiments, suggesting that the model-based description of the Al-Ni-Si-Y system can serve as a guidance to design the novel NiSiAlY alloys in resisting harsh salt-spray environment.