Akademik Veri Yönetim Sistemi
CERAMICS INTERNATIONAL, cilt.49, sa.11, ss.18786-18799, 2023 (SCI-Expanded)
Current study investigates the manufacturability, metallographic and mechanical characterization of the functionally graded Fe/Fe2B composites processed by in-situ powder metallurgy (IPM) using iron (Fe) and boron carbide (B4C) particles. Using powder forms of Fe and B4C particles, the opposite outer surfaces of the FGMs acquired high toughness and hardness, respectively. Moving from one surface which was reinforced with 100 %Fe, the B4C content was gradually increased to reach 20 %B4C providing functional transition from soft to hard surfaces. Three different compositional gradients were used which increased moderately (n:0.1), linearly (n:1), and rapidly (n:5) depending on the content of reinforcement B4C particles within the layers. The functional gradient enhanced the tendency of transition from the metallic to ceramic phases which accelerated with increasing reinforcement ratios. While optical and scanning electron microscopy were used to characterize the microstructure along with the hardness determination of FGMs for each constituent layer, static and dynamic loading behaviors of the FGMs were analyzed by bending and impact tests, respectively. Specimens were loaded from both, 100 %Fe and 20 %B4C surfaces representing the soft and hard sides of the FGMs. Microstructural analyses revealed the presence of Fe2B phases which were in situ synthesized after the B4C reacted with the iron. While the top layer was completely covered by boride phases, it showed the presence of phases even in the lower reinforced layer. Both the fraction of Fe2B phases as well as the hardness of the remaining layers were dictated by the content of B4C particles in the layers. While the hardness of the material was increased due to Fe2B phases, the hardness gradient was also in proportion with the increase in the reinforcement ratios. For each gradient, maximum hardness was achieved for the highest reinforced top layer. The maximum force and fracture energy depended on the surface under force; 100 %Fe or Fe+20 %B4C. FGMs loaded from the 100 %Fe surface showed an overall brittle behavior and those loaded from 20 %B4C surface showed an overall ductile behavior due to load distribution between the hard and soft layer. Additionally, the peak fracture force and fracture energy decreased with the increasing compositional gradients regardless of the types of impacted surface.