The effect of sintering temperature on the strength of powder copper subjected to repeated pressing

1. Sintered copper produced by repeated pressing and sintering at low temperatures is markedly superior to cast commercial copper in hardness and resistance to compression. 2. High-temperature sintering is not essential for obtaining powder copper with a minimum pore content. Low porosity may be attained by repeated compaction and annealing at relatively low temperatures. 3. The mechanical properties of sintered copper increase with decreasing sintering temperature. When materials obtained at different sintering temperatures are compared with one another and with cast copper, it is found that the greatest difference in the resistance to compression is observed at low degrees of deformation. 4. The deterioration of mechanical properties and improvement of ductility at higher sintering temperatures may be explained by grain growth and a coarsening of the block structure. 5. The X-ray diffraction method of studying recrystallization, involving determination of the number of spots on interference lines in X-ray photographs, fails to detect the process of collective recrystallization during the sintering of compacts from electrolytic copper powder at up to 1000°C.