Showing papers by "Elisa Maria Ruiz-Navas published in 2004"
TL;DR: In this paper, the authors investigated the performance of a composite material reinforced with zirconium diboride by mechanical alloying followed by cold pressing and hot extrusion, and compared the results with the same composite produced by conventional powder metallurgy (PM), and showed that the incorporation of the ZrB2 particles produces only a small increase in the material hardness, but a small decrease in the UTS.
Abstract: The homogenous distribution of the reinforcement phase is an essential condition for a composite material to achieve its superior performance. Powder metallurgy (PM) can produce metal matrix composites in a wide range of matrix reinforcement compositions without the segregation phenomena typical of casting processes. Particularly, mechanical alloying can be used to mix the matrix and reinforcement particles, enhancing the homogeneity of the reinforcement distribution. This work investigates the production of aluminium 6061 reinforced with zirconium diboride by mechanical alloying followed by cold pressing and hot extrusion, and compares the results with the same composite produced by conventional PM and hot extrusion. The incorporation of the ZrB2 particles produces only a small increase in the material hardness, but a small decrease in the UTS when conventional PM is employed. Mechanical alloying breaks the reinforcement particle clusters, eliminates most of the cracks present in the surface of the reinforcement particles, decreases its size and improves its distribution. This enhancement of the composite structure, in addition to the metallurgical aspects promoted by mechanical alloying in the matrix, brings approximately 100% improvements in the composite UTS and hardness, compared with the composites obtained by PM.
67 citations
TL;DR: In this article, the authors investigated the properties of composite materials reinforced with aluminum AA6061 matrix composite materials by powder metallurgy techniques and hot extrusion and found that the higher reinforcement content results in higher particles dispersion hardening.
48 citations
TL;DR: In this paper, a material constituted by an iron matrix and a 50 % wt of WC and TaC carbides is developed, and the green compacts were sintered at different temperatures and properties like hardness and density were determined.
Abstract: The objective of this study aims to the development of Fe-matrix composites with high carbide content to achieve properties between high-speed steels (HSS) and cemented carbides. Cemented carbides are harder and show higher wear resistance than HSS, but lower toughness. Besides, the substitution of Co or Ni for other binders is desirable due to the carcinogen character of these metals. In this work, a material constituted by an iron matrix and a 50 % wt of WC and TaC carbides is developed. High-energy milling has been used to obtain composite powders presenting a good bonding and homogeneous distribution of the carbides in the matrix. Those powders were characterised and compacted by die pressing. The green compacts were sintered at different temperatures, and properties like hardness and density were determined. Also, the wear behaviour was studied and microstructural analysis by SEM was carried out to complete the study.
6 citations
TL;DR: In this paper, the influence of reinforcement and milling technique on the unreinforced base alloy corrosion resistance is analyzed, and the most significant results reveal the influence that reinforcement and blending techniques have on the corrosion and pitting potential.
Abstract: This work tries to analyze the corrosion behavior of a serie of composite materials, as well as to study the influence of the reinforcement and milling technique on the unreinforced base alloy corrosion resistance. For this purpose composite materials, base 6061 aluminum alloy and reinforced with Si 3 N 4 , ZrB 2 and AlN (5% wt.) have been manufactured, by means of both low and high energy milling techniques for the blending step. The study is mainly focused on the evolution of the corrosion potential versus time, pitting potential as well as the pasive zone of each material by means of continuous current electrochemical techniques. The most significant results reveal the influence of the reinforcement as well as the employment of different blending techniques, both on the corrosion and pitting potential.
1 citations