Synthesis and Characterization of Nano-Y2O3 Dispersed Zr-based Alloys by Mechanical Alloying and Conventional Sintering

Abstract

In the present study alloy powders with nominal composition of 65.0Zr–20.0Fe–10.0Cu– 5.0Ti (alloy A), 64.0Zr–20.0Fe–10.0Cu–5.0Ti–1.0(Y2O3) (alloy B), 55.0Zr–20.0Fe– 20.0Cu–5.0Ti (alloy C) and 54.0Zr–20.0Fe–20.0Cu–5.0Ti–1.0(Y2O3) (alloy D) (in wt. %) were synthesized by mechanical alloying (MA) followed by conventional sintering at 1050C temperature. Phase evolution and microstructure characterization during milling and after consolidation were characterized by using X- ray diffraction (XRD) and scanning electron microscope (SEM) analysis. An individual element goes into solid solution with increase in milling time and after 10h of milling complete solid solution was observed in all the alloy powders. The XRD analysis revealed that an increase in lattice strain and decrease in crystallite size with increase milling time. The final average particle size of mechanical alloyed powders at 10 hours of milling was in the range of 50-55 nm. The bulk density and hardness of sintered products were found to increases with the presence of dispersion of Y2O3 in Zr matrix. Alloy D sintered at 1050°C exhibits maximum hardness of 2.775 GPa which was 1.5 to 2 times higher than that of the commercially available Zr alloy. The wear tests indicate similar trends as that of hardness and abrasion was the predominant wear mechanism