Rapid Synthesis of V-4Cr-4Ti Alloy/Composite by Field Assisted Sintering Technique

Abstract

The present investigation deals with synthesis and characterization of V-4Cr-4Ti composite/alloy from unmilled and mechanically alloyed powders. Starting powders were sintered by field assisted sintering technique with varying process parameters viz., temperature, holding time, etc. Both powder and sintered samples were subjected to microstructural and morphological characterization by using scanning electron microscopy and phase analysis was done with the help of X-ray diffraction. Field assisted sintering of unmilled and milled powders has resulted in V-4Cr-4Ti composite and single phase V-4Cr-4Ti alloy. Differential thermal analysis was performed in powder samples to identify the recovery and recrystallization regimes of starting powders. Activation energy of the starting powder was calculated by Kissinger analysis. Field assisted sintering of mechanically alloyed powders resulted in nanostructured single phase V-4Cr-4Ti alloy whereas sintering of unmilled powders resulted in V-4Cr-4Ti composite. X-ray diffraction analysis confirms nanostructured single phase V-4Cr-4Ti alloy after field assisted sintering of milled powders. For identical sintering condition, unmilled V-4Cr-4Ti powders have consumed 75% more current than milled powders. Role of particle size, shape and their distribution on the densification behavior of V-4Cr-4Ti powders are also discussed. Interstitial contamination in the sintered samples were studied using electron probe micro-analysis. Microhardness experiments were done on the sintered samples and their corresponding Hall-Pitch plots were deduced.