No abstract

In this study, WE43 alloy matrix composites, reinforced with 2.5, 5, 7.5, and 10 wt% B4C particles have been produced by the stir casting technique at 750 °C. Cast ingots of the matrix alloy and the composites were then subjected to hot rolling at 480 °C. After that, the effect of B4C additions (0–10 wt%) as well as hot rolling on the microstructure and mechanical properties of WE43 alloy were investigated. Microstructural characterization following hot rolling revealed a relatively uniform distribution of B4C particles, well-bonded B4C particles to the matrix, and a minimal porosity level. Further, both as-cast and hot-rolled composites have shown considerable grain refinement and hence improved mechanical properties compared to unreinforced alloy. Twinning was the dominant deformation mechanism in the hot-rolled WE43 alloy, whereas dynamic recrystallization occurred extensively in hot-rolled composites. It was observed that tensile strength and hardness values were improved not only as B4C content increased but more due to the rolling effect; however, elongation to fracture was reduced. Maximum ultimate tensile strength of ∼284 MPa and yield strength of ∼259 MPa with an improved hardness to ∼97 HB were obtained for the hot-rolled WE43-10%B4C composite.

In this study, sintering was investigated for making SiAlON by utilizing low cost Si3N4, Al2O3 and AlN powder precursors. These materials were mixed by mechanical ball milling, then processed by pressureless sintering or spark plasma sintering methods and the properties compared. XRD spectroscopy showed nano-scale and amorphous phases, which were produced after longer milling time. Investigation of the bulks after sintering revealed that increasing the pressureless sintering temperature resulted in an increase in density and mechanical properties of the specimens, as did changing the sintering technique from pressureless to spark plasma sintering. Furthermore, the wear mechanisms of adhesive or micro-abrasion of the rubbed surfaces were confirmed.