Effect of the heating rate and Y2O3 coating on the microstructure of Wf/ Y2O3/W composites via field assisted sintering technology

Field assisted sintering technology (FAST) is one of the potential methods to fabricate tungsten fiber reinforced tungsten (Wf/W) composites. The microstructure and mechanical properties of Wf/W composites are closely related to the sintering parameters. In the present work, the Wf/W composites with a Y2O3 coating on the fiber (Wf/Y2O3/W) were fabricated via a FAST process and the microstructure was characterized. The influence of the heating rate and Y2O3 coating on the microstructure of Wf/Y2O3/W composites was discussed in detail. It is observed that the Y2O3 coating can get damaged and move into the adjacent matrix. A higher heating rate (100 degrees C/min) causes more serious damage on the Y2O3 coating which could be attributed to the higher electric current intensity. The samples produced with a lower heating rate (50 degrees C/min) or with a thicker Y2O3 coating (3 mu m) show an interface with better continuity. In addition, the integrity of the Y2O3 coating could by protected by an additional W-coating produced by chemical vapor deposition (CVD).