Effect of copper on the mechanical properties of alloys formed by powder metallurgy

• Alloys of 0.6 C, 1.0 Ni, 0.3 Mo, 0.7 Mn (wt%) and the rest Fe are doped with 8 wt% Cu.
• Cu is added to improve the properties of alloys formed by powder metallurgy.
• Cu's effect on the strength, microstructure and fracture of the alloys is examined.
• Cu doping increases toughness and density and decreases porosity of the alloys.
• A part containing the Cu alloy tolerated 65% more operational cycles than one without.

Alloys formed by powder metallurgy are typically porous, which reduces their strength. In this study, we attempt to improve the mechanical properties of an alloy composed of 0.6 wt% C, 1.0 wt% Ni, 0.3 wt% Mo, 0.7 wt% Mn and the balance Fe by addition of 8 wt% Cu. To form the alloys, powders are blended and compacted in a dual-action hydraulic press and then sintered in a furnace at 1150 °C. Alloys with and without Cu are used in specific parts designed for impact testing. Stress analysis is performed using ANSYS, which validates the operation of the parts. The strength of the body geometry according to its design is determined by considering the manufactured material and the loads that it is subjected to during operation. SEM images revealed that the alloy without Cu contains martensite and bainite phases with large, irregular pores. In contrast, the alloy with Cu has a considerably lower pore concentration. During sintering, Cu forms a liquid phase that can fill the spaces between the particles of the alloying powders. The result is an alloy with increased density and toughness; the density of the alloy increases from 7.2 to 7.8 g/cm3 upon addition of Cu, and its toughness increases from 22 to 34 J.

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