Ahmed E. Nassef; A. I. Alateyah; Medhat A. El-Hadek; W. H. El-Garaihy
Abstract
The physical and mechanical properties of atomized prealloyed Fe-Cu powders, blended with different amounts of liquid additions of lead (Pb), were studied in the as-sintered condition and hot compaction techniques. The influence of Pb content, compacting pressure and temperature on the densification, ...
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The physical and mechanical properties of atomized prealloyed Fe-Cu powders, blended with different amounts of liquid additions of lead (Pb), were studied in the as-sintered condition and hot compaction techniques. The influence of Pb content, compacting pressure and temperature on the densification, hardness, and the mechanical properties were investigated. During hot compaction, at a temperature of 500 ° C, the Pb liquid was found to spread uniformly among Fe-Cu solid particles. The effect of pores in Fe-Cu-Pb alloys, generated by sintering with transient liquid phase, had been studied. An attempt was made in order to study the properties of Fe-Cu-Pb particles and their behaviour, with respect to the consolidation of Fe-Cu-Pb powders. The density values of cold and hot compacts, at various pressures and temperatures values, were reported. The microstructure, hardness, and strength measurements were found to be dependent upon the compacting pressure. For the cold compacted alloys, the Pb powder particles were completely melted to form liquid pools. In addition, increasing the Pb content in the alloy matrix revealed a decrease of the pores percentage, hence the sample became denser. On the other hand, grain was found to be coarser and less porosity is obtained with increasing the Pb content in the hot compacted. It is found that, increasing the compacting pressure of the cold and hot compacted samples revealed a homogenous, fine grain, and small pores appeared around the grain boundaries. The mechanical properties data showed improvement in the strength and hardness of the hot and cold compacted samples by increasing either the compaction pressure or temperature.
Ahmed E. Nassef; A.I. Alateyah; Medhat A. El-Hadek; W. H. El-Garaihy
Abstract
In this study, elemental Cu and Sn powder were mechanically mixed forming different Cu-Sn alloys. To ensure uniformity of the particle shapes, the Cu, and Sn were mechanically milled and mixed in an agate rock mortar, with high energy ball mill for half an hour, with different weight ratios according ...
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In this study, elemental Cu and Sn powder were mechanically mixed forming different Cu-Sn alloys. To ensure uniformity of the particle shapes, the Cu, and Sn were mechanically milled and mixed in an agate rock mortar, with high energy ball mill for half an hour, with different weight ratios according to the composition design. The milling of the powders resulted in uniform sphere-like particles for Cu–Sn alloys. Hot compaction was performed in a single acting piston cylinder arrangement at room temperature. All hot pressed MMCs were heat-treated at about 550°C to allow the atoms to diffuse randomly into a uniform solid solution, as liquid phase sintering. Vickers micro-hardness measurements were carried out for the hot-pressed Cu–Sn alloys. Cylindrical specimens of aspect ratio of ho/do = 1.5 were tested under frictionless conditions at the compression platen interface. Charpy transverse rupture strength had been used to determine the fracture strength of the different Cu-Sn alloys. Fracture surface features of the different Cu-Sn alloys were characterized using scanning electron microscopy. It had been found that, the 85%Cu–15% Sn alloy revealed an increase of hardness values, a decrease of the yield strength, and an increase in the impact energy by 26.2, 23, and 18.7%; respectively, compared with the Sn-free alloy. The Cu-Sn alloys showed an apparently classical inclined fracture surface, at about 45 o with the applied stress axis, which was similar to what’s obtained for a diversity of hard metals.
