Grain growth and sintering characteristics of Ni–Cu alloy nanopowders consolidated by the spark plasma sintering method

Ni–Cu bulk alloys are successfully prepared by the spark plasma sintering (SPS) technique using nanopowders obtained from the arc plasma evaporation method. The grain growth of Ni–Cu nanopowders during the SPS process is studied based on the classical phenomenological kinetic theory. The kinetic grain growth exponent, n, and the apparent activation energy, Q, are determined using the plot method. The calculation results exhibit that the n values vary at different sintering temperatures, whereas the Q values at low temperature are always higher than at high temperature regardless of the n values. The mechanical properties such as yield strength, tensile strength and ductility of the sintered specimens at different temperatures and raw alloy ingots are studied by tensile test. The density of the sintered samples increases with increasing sintering temperature, in contrast to the behavior of the tensile strength and yield strength of the Ni–Cu bulk alloy sintered by SPS at different temperatures. The mechanism strength of the sintered specimens is attributed to the microstructure characteristics of the specimens at different temperatures, which is further discussed with the classical reinforcement theories.