Effect of reinforcement-particle-orientation anisotropy on the tensile and fatigue behavior of metal-matrix composites
- PDF / 281,443 Bytes
- 9 Pages / 684 x 858 pts Page_size
- 64 Downloads / 224 Views
INTRODUCTION
THE combination of ceramic particles and a light-metal matrix results in a composite material with improved stiffness, strength, fatigue resistance, and wear resistance, when compared to the unreinforced light alloy.[1–4] The microstructure and mechanical properties of particle-reinforced metal-matrix composites (MMCs) are inherently dependent on several factors such as matrix microstructure,[5,6,7] reinforcement volume fraction, size, morphology, and distribution.[8–14] Processing plays an important role in determining the inherent characteristics of the matrix, reinforcement, and composite.[1] Thus, processing-induced changes in the microstructure of the composite will have important implications on the mechanical behavior of the material. Several processing techniques have been used to fabricate particle-reinforced MMCs. These are generally classified as liquid-phase[15] or solidphase processes.[16] Liquid-phase processes, such as casting or infiltration, are typically more cost-effective than solidphase processes. The main drawback associated with these techniques is the difficulty in controlling particle distribution and obtaining a uniform matrix microstructure.[15] Furthermore, an interfacial reaction between the matrix and the reinforcement often takes place, which has an adverse effect on the mechanical properties of the composite.[17] The most common solid-phase processes are based on powdermetallurgy processing.[16] The ceramic and metal powders are mixed, isostatically cold compacted, and hot pressed to full density. The fully dense compact then typically undergoes a secondary operation such as extrusion or forging.[18] Novel low-cost approaches, such as sinter forging, have aimed at eliminating the hot-pressing step, with promising results.[19] One of the important attributes of extrusion processing of particle-reinforced MMCs is the alignment of particles along V.V. GANESH, Graduate Research Associate, and N. CHAWLA, Associate Professor, are with the Department of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287-6006. Contact e-mail: [email protected] Manuscript submitted June 30, 2003. METALLURGICAL AND MATERIALS TRANSACTIONS A
the extrusion axis and refinement of the matrix grain size.[14,20] While several investigators have examined the tensile and fatigue behavior of these materials, the properties of the material are typically measured parallel to the extrusion axis.[5–14] Very few studies have attempted to examine the effect of extrusion-induced particle-orientation anisotropy on the microstructure and mechanical behavior of particle-reinforced MMCs.[21,22] Logsdon and Liaw[21] studied the tensile-strength anisotropy behavior in SiCparticle and whisker-reinforced aluminum alloys and noted that the strength was higher parallel to the extrusion axis than perpendicular to the extrusion axis. Jeong et al.[22] also noted a higher Young’s modulus of the composite along the extrusion axis. In this study, we have examined the microstructure and mechanical-behavior
Data Loading...
