Development of High-Performance SiCp/Al-Si Composites by Equal Channel Angular Pressing

Abstract

Relatively low compactness and unsatisfactory uniformity of reinforced particles severely restrict the performance and widespread industry applications of the powder metallurgy (PM) metal matrix composites (MMCs). Here, we developed a combined processing route of PM and equal channel angular pressing (ECAP) to enhance the mechanical properties and wear resistance of the SiC p /Al-Si composite. The results indicate that ECAP significantly refined the matrix grains, eliminated pores and promoted the uniformity of the reinforcement particles. After 8p-ECAP, the SiC p /Al-Si composite consisted of ultrafine Al matrix grains (600 nm) modified by uniformly-dispersed Si and SiC p particles, and the composite relative density approached 100%. The hardness and wear resistance of the 8p-ECAP SiC p /Al-Si composite were markedly improved compared to the PM composite. More ECAP passes continued a trend of improvement for the wear resistance and hardness. Moreover, while abrasion and delamination dominated the wear of PM composites, less severe adhesive wear and fatigue mechanisms played more important roles in the wear of PM-ECAP composites. This study demonstrates a new approach to designing wear-resistant Al-MMCs and is readily applicable to other Al-MMCs.nanostructured Al/SiC-graphite composite by accumulative roll bonding (ARB) and showed that a homogeneous ultra-fine grain structure and uniform distribution of particles could be obtained by eight ARB cycles. Haghighi et al. [18] revealed that the Al-5 vol.% nano-Al 2 O 3 composite consolidated by equal channel angular pressing (ECAP) possessed higher mechanical properties and hardness. In addition, twist extrusion (TE), as a potent tool for obtaining advanced engineering materials, can be used to improve the mechanical and tribological properties of MMCs [22,23].The tribological property is crucial to components sustaining wear. As important wear-resistant materials, Al-MMSs have been employed for vehicle discs. The optimized microstructure, especially the refined matrix grains, and improved mechanical properties of Al-MMCs by SPD lead to enhanced wear resistance. It was suggested that through the grain refinement, the wear-resistance of MMCs and some alloys can be improved to follow a linear relation with the d −0.5 (d is the average grain size), resembling the Hall-Petch effect [24][25][26][27]. However, there have been very limited reports in the literature dealing with the wear behavior of SPD-MMCs up to date, and among a few publications, there were conflicting results reported. Haghighi et al. [18,28] compared the Al-MMCs processed by ECAP or conventional extrusion and concluded that the ECAP samples possessed better wear resistance than the extruded counterparts. The improved wear resistance was attributed to pore elimination, homogeneity of the particle distribution and grain refinement by the ECAP. Similarly, enhanced wear resistance of Al-MMCs by ARB was reported by Darmiani [29]. However, decreased wear resistance was also reported by Jamaati et al. [26], who...

Enhancement of Mechanical Properties and Rolling Formability in AZ91 Alloy by RD-ECAP Processing

“…This RD-ECAP equipment can achieve high ECAP deformation passes with one-time loading and unloading, which can protect samples and improve efficiency. Our research group has applied RD-ECAP on various materials to achieve grain refinement and property improvement [23,33,34,35,36,37]. Recently, up-scaled RD-ECAP equipment was developed and put into use (sample dimension of 50 mm × 50 mm × 100 mm).…”

Interface Structure and Mechanical Properties of 7075Al Hybrid Composite Reinforced with Micron Ti Metal Particles Using Pressure Infiltration

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