Powder Metallurgy Group Meeting,Coventry, 24–26 October 1977: Report of Proceedings

Abstract

The feasibility of producing room temperature superplastic Zn–Al alloys by hot extrusion of gas atomised powders has been investigated. Commercially pure zinc, and Zn–8wt-%Al and Zn–28wt-%Al binary alloys were gas atomised; the resulting powders were cold compacted into cylindrical billets and extruded to form consolidated rod. Two extrusion temperatures (200 and 300°C) were used, chosen to lie on either side of the invariant (eutectoid) temperature of 275°C. It has long been established that in conventional cast alloys rapid quenching from above this temperature is required to produce a microstructure having superplastic properties. (It was anticipated that the 300°C extrusions would contain quantities of near equilibrium eutectoid and thus be unlikely to deform superplastically. The 200°C extrusions were expected to exhibit a non-equilibrium structure that might have potential in terms of superplastic deformation.) The microstructures of the extrudates were investigated by transmission electron microscopy and the mechanical properties established by room temperature tensile testing and Charpy impact testing. PM/0502     

Powder Metallurgy Group Meeting,Stratford-Upon-Avon, 3–4 November 1975: Report of Proceedings

Abstract

The key steps of a PM technique for manufacturing fully dense near net shape tool steel parts are described. The main production steps are powder preparation, compaction, and sintering. The pre- alloyed powders used in the process are annealed to soften them, making compacting to fairly high green densities possible. Sintering to full density is accomplished at a closely controlled temperature near the solidus of the material. The heat treatment response of sintered high-speed steel parts is similar to that of conventionally produced steels. A model for the calculation of the necessary carbon content to achieve full hardness during the heat treatment of high-speed steels was developed. The model is based on predicting the amount and approximate chemical composition of the carbides present after quenching from the austenitizing temperature and the subsequent calculation of the carbon tied up within the carbides. PM/0207     

Mechanical and Tribological Behavior of Powder Metallurgy Processed Aluminum–Graphite Composite

Russian Journal of Non-Ferrous Metals - In this research, the mechanical and tribological behavior of aluminum–graphite (Al–Gr) composite has been investigated in order to determine the...     

Properties of Ni–Cr–Al Alloys Obtained by a Powder Metallurgy Method

Alloys of practically 100% density were formed by hot pressing mixtures of nickel, chromium and aluminum powders. The principal phases formed are solid solutions based on chromium, on nickel, and also the intermetallic NiAl. These correspond to phases in the phase equilibrium diagram of theNi Cr Al system. The strength and wear resistance of the alloys are determined by the ratio of phase components.     

Evaluation of Mechanical and Tribological Behavior of Al–4 %Cu–x %SiC Composites Prepared Through Powder Metallurgy Technique

This article presents characterization of 99.85 % pure aluminum with 4 % copper, reinforced with varying proportions of silicon carbide. Al–Cu–SiC metal matrix composite (MMC’s) are prepared by powder metallurgy route for 0, 2.5, 5, 7.5, 10, 12.5 and 15 % of SiC addition. To investigate the effects of adding SiC particles, microstructural analysis and mechanical properties by micro-hardness, compression, wear and thermal conductivity are studied. Scanning electron microscope image shows uniform distribution of particulates. Results show that upon increasing addition of SiC particles, micro-hardness and compression strength increases, whereas thermal conductivity decreases. Wear rate increases till 7.5 % SiC addition, with further addition of SiC, wear rate increases due to the un-bonding of SiC particles from the MMC, aiding in the increase of wear rate. Addition of SiC up to 7.5 % play an important role in improving wear resistance, thermal and mechanical properties of Al–Cu–SiC MMC.     

Strength–Ductility Property Maps of Powder Metallurgy (PM) Ti-6Al-4V Alloy: A Critical Review of Processing-Structure-Property Relationships

Metallurgical and Materials Transactions A - A comprehensive assessment of tensile properties of powder metallurgical (PM) processed Ti-6Al-4V alloy, through the mapping of strength–ductility...     

Effect of Graphite and SiC Addition into Cu and SiC Particle Size Effect on Fabrication of Cu–Graphite–SiC MMC by Powder Metallurgy

Here we have reported individual and combined effect of graphite and SiC into Cu matrix during fabrication of Cu–graphite–SiC hybrid metal matrix composite by powder metallurgy. Mechanical properties of the composites are enhanced by simultaneous addition of 1, 3, 5, 10 and 15 vol. % of graphite along with 2, 5 and 10 wt. % of SiC into pure Cu, whereas electrical conductivity deteriorates. Composites are fabricated by cold compaction of composite powder mixture followed by conventional sintering in a tubular furnace at 900 °C for 1 h in argon atmosphere. For comparison, SiC powder size of 5 and 50 µm are used to study the effect of SiC particle size on microstructure, mechanical and electrical properties of the composites. Optical microscopy and scanning electron microscopy reveal the homogeneous distribution of graphite and SiC in matrix and good compatibility between Cu–graphite and Cu–SiC particles. Hardness of the composites decreases with increase in graphite and increases with increase in SiC content. Composites containing fine SiC particles show higher hardness value as compared to coarse particles. Maximum Vickers hardness value of 75 is obtained for Cu-1 vol. % graphite-10 wt. % SiC composite. Electrical conductivity decreases with increase in both graphite and SiC content. Composites containing coarse SiC particles exhibit higher electrical conductivity than fine SiC.