Development of Nano-Y2O3 Dispersed Zr Based Alloys Synthesized by Mechanical Alloying and Consolidated by Pulse Plasma Sintering

Abstract

In this paper, Zr based alloys are synthesized with nominal compositions: 50.0Zr-30Fe- 10Cr-5.0Cu-5.0Ti(alloy A),49.0Zr-30Fe-10Cr-5.0Cu-5.0Ti-1.0 Y2O3 (alloy B), 50.0Zr-25.0Fe- 10Cr-10Cu-5.0Ti (alloy C), and 49.0Zr-25.0Fe-10Cr-10.0Cu-5.0Ti-1.0 Y2O3 (alloy D) (all in wt %) by mechanical alloying and consolidated by pulse plasma sintering (PPS) method at 1173 K (900°C), 1223 K (950°C) and 1273 K (1000°C) using 75 MPa uniaxial pressure applied for 5 min and 70 kA pulse current at 3 Hz pulse frequency. The microsturctural and phase evolutions during mechanical alloying and sintered products have been characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM & TEM) and energy dispersive spectroscopy (EDS). Mechanical properties in terms of hardness and compressive strength were determined by using nano-indentation unit and universal testing machine. The present alloys recorded very high levels of compressive strength (1359-2456 MPa), and hardness (7.0-10.0 GPa) which measures 1.5-2.0 times more than that of other Zr alloys (< 1000 MPa) as available in literature. The microstructure of the Zr matrix containing uniform dispersion of nanomertic (10-20 nm) oxide (Y2O3) particles can be attributed to grain boundary pinning, creep resistance and oxidation at elevated temperature.