Microstructure and mechanical properties of Hot Isostatically Pressed with three different diameter distributions of Ti-6Al-4VELI alloy spherical powders

Abstract:

We report the microstructural and mechanical analysis of Ti-6Al-4VELI (Extra Low Interstitial) alloy parts fabricated with three diameter distributions of Ti-6Al-4VELI spherical powders by Hot Isostatic Pressing (HIP), which were manufactured via plasma rotating electrode processing (PREP). The powders were canned and pressed at temperatures 940℃ and pressure 120MPa. Alpha-beta mixed phases in the specimens were observed through Optical Microscope (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) methods, respectively. The results show the microstructures of specimens were found to be strongly dependent on the different distributions of powders. The samples formed from fine powders (particle size range from 45μm to 100μm) shows better microstructure properties to those formed from medium powders (particle size range from 100μm to 150μm) and coarse powders (particle size range from 150μm to 250μm). In addition, the billets formed from fine powders exhibited higher tensile strength and ductility than those formed via medium powders and coarse powders. These results were attributed to the initial microstructures of HIP samples, as confirmed by evaluating their fracture features