Effect of tungsten micro-scale dispersed particles on the microstructure and mechanical properties of Ti-6Al-4V alloy

Ti-6Al-4V (TC4) alloy and Ti-6Al-4V-5 wt.%W (TC4-5%W) alloy were fabricated by spark plasma sintering (SPS). The crystalline structure and microstructure of both TC4 alloy and TC4-5%W alloy were confirmed using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), respectively. The XRD patterns suggested that a similar crystalline structure was formed in both of TC4 alloy with and without the W addition. SEM and TEM indicated that the dispersed W particles can refine the beta grains, alpha colonies and coarsen the alpha laths by acting as the supernumerary nucleation sites for alpha laths during the beta -> alpha+beta transformation process. Moreover, a comparative analysis of the mechanical properties of both TC4 and TC4-5%W alloys was obtained by the tensile tests, which is found that the W addition can increase the strength and ductility of TC4 alloy simultaneously. It is found that fine-grain strengthening is the dominant strengthening mechanism, which contributed 72% of the total strength increment. Meanwhile, the load-bearing effect also contributes to some of the total strength increments in this study. This study concluded that TC4 with W dispersed particles had a great potential to use as a novel Ti alloy with high strength and good ductility. (C) 2020 Elsevier B.V. All rights reserved.