The dry sliding wear behavior of magnesium-matrix-composites (MMC) reinforced by boron carbide particulates (B4Cp) has been investigated. Magnesium is the lightest structural material and is a good choice as a metal matrix for boron carbide and silicon carbide addition. Magnesium and its alloys, without reinforcement, are generally not suitable for mechanical applications due to their low wear resistance. The MMCs used in this study were produced via highpressure die-casting technique. The wear resistance of B4C/AZ91D composite reinforced with 12 and 25 wt% B4C were studied, compared with unreinforced diecast AZ91D. As-cast microstructures of the materials and boron carbide particules were characterized by using Scanning Electron Microscopy (SEM). The hardness values of the control sample and the composites were determined via Vickers hardness measurements. Pin on disk dry sliding wear tests were carried out to study wear rate and wear mechanisms. The magnesium matrix composites were used as pins while mild steel as disc material. The worn surfaces of pins were examined by using SEM. The wear performance of magnesium matrix composites was improved with increasing volume fraction of B4C up to a certain level.

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The driving force behind the efforts to develop magnesium metal matrix composites (MMC) via high-pressure die casting is the requirements for advanced applications under severe operational conditions in terms of stress, temperature, and corrosion resistance. Therefore this study aims to explore the mechanical properties of die cast Mg-MMC in terms of hardness and strength, as well as its corrosion resistance. AZ91D was chosen as the most commonly used magnesium alloy. The choice as the reinforcement agent that has to be an economical and non-reactive addition was silicon carbide particles (SiC P ) with an average particle size of 10 lm. The challenge was production of high quality, homogeneous material with good mechanical properties and acceptable corrosion resistance. The results revealed the advantages of a die cast Mg-MMC as a new attractive alternative for advanced structural applications that can be used for mass production.

High pressure die casting (HPDC) is the dominant process for the production of magnesium components with complex configuration having typically thin to medium wall thickness. The growing use of die cast Mg alloys in the automotive industry, particularly for the production of drive-train components, has led to the development of creep resistant alloys, MRI153M and MRI230D, which were launched into the market several years ago. The present paper aims at exploring the effect of the HPDC process parameters on the porosity and, as a result, on the properties of the two MRI's developed alloys in comparison with common alloys AZ91D and AM50A that are usually considered as benchmark die casting alloys. The outcome of the research performed includes processing guidelines and recommendations, which allow obtaining high quality sound castings. These recommendations should be implemented in the course of design, optimization and production of highperformance components for various applications.

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