Synthesis of titanium orthorhombic alloy spherical powders by mechanical alloying and plasma spheroidization processes

Abstract

Abstract The current study demonstrates the feasibility of mechanical alloying (MA) and plasma spheroidization (PS) processes to produce highly-spherical Ti-22Al-25Nb-0.3Mo-1Zr-0.3Si-0.2Hf-0.4Ta (at.%) orthorhombic alloy powders. The microstructure, chemical homogeneity and phase evolution of the obtained powders at different times of milling and after plasma spheroidization were investigated using X-Ray Diffraction and Scanning Electron Microscopy methods. MA at short milling times resulted in powders with highly inhomogeneous layered microstructures with HPC- and BCC-crystal structures. Increasing the milling time promoted the formation of B2/β-phase solid solution and improved the chemical homogeneity. PS of the fabricated irregular powders allowed to produce powders of the orthorhombic alloy with homogeneous chemical composition and a high degree of sphericity with the microstructure consisting of dendritic B2-phase.