Fabrication and performance evaluation of trapezoidal surface-layered functionally graded composites via a novel separator-assisted powder metallurgy technique

Abstract

Traditional powder metallurgy (PM) techniques typically produce functionally graded composite materials (FGCMs) with planar interfaces, which limit the design possibilities and mechanical performance of the resulting materials. In this study, a novel separator-assisted molding technique was developed to fabricate FGCMs with non-planar interfaces. This technique utilizes adjustable separators to control the precise volume of each graded layer. Utilizing this method, three-layer FGCMs consisting of 0, 30, and 60 wt% B 4 C, as well as four-layer FGCMs with 0, 20, 40, and 60 wt% B 4 C reinforcement, were successfully fabricated. The microstructure, density, hardness, and transverse rupture strength (TRS) of the produced FGCMs were systematically evaluated. Microstructural characterization via SEM revealed that the reinforcement was uniformly distributed within the low-wt.% B 4 C layers, showing no evidence of delamination or macroscopic porosity. Hardness data were statistically analyzed using Levene’s test for homogeneity of variance, followed by a one-way ANOVA. Tukey’s post hoc test was subsequently applied to detect significant differences between the groups (p < 0.05). The highest Brinell hardness was obtained from the four-layered FGCM containing 40 wt% B 4 C, reaching 161 HBW. TRS data were validated via Levene’s test and statistically analyzed using a two-way ANOVA to evaluate the effects of the number of layers and the tested surface type. The maximum TRS value was achieved by the four-layered FGCM at 628,56 MPa, specifically when the load was applied to the reinforced surface. Overall, the results demonstrate that the separator-assisted molding technique effectively produces FGCMs with complex interfaces and enhanced mechanical properties, holding great promise for advanced structural applications.