Abstract Scope |
Thermal stability of nanocrystalline Ni-Y-Zr duplex alloys, wherein both grain boundary segregation (some solid solubility of Zr in Ni) and phase formation (e.g., Ni-Y and Ni-Zr precipitates) occur, was investigated. The initial materials with different compositions were synthesized using ball-milling. The microstructural changes after annealing (up to 1473K) were characterized using X-ray-line-broadening, micro-hardness, ion beam channeling contrast imaging, and transmission electron microscopy. Results demonstrated that the rate of grain growth observed in Ni-Y-Zr ternary alloy at 873K is similar to the growth rate in pure NC-Ni at 373 K. Furthermore, the maximum hardness of 753 HV was obtained for Ni-Y-Zr ternary system at 873 K, approximately 60 HV greater than Ni-Y, Ni-Zr binary alloys, and more than double as compared to pure NC-Ni. Overall, the thermal stability of ternary alloy has been enhanced due to the presence of Y and Zr. |