Synthesis of Ni-Cu Heterostructures with SPS to Achieve a Balance of Strength and Plasticity

Abstract

The balance between strength and plasticity has always been an urgent problem for researchers to solve. In this experiment, Ni-Cu heterostructures (HSs) were synthesized by spark plasma sintering (SPS), rolling deformation, and subsequent heat treatment. The density of the Ni/Cu interface of Ni-Cu HS materials can be independently tuned, and thus the effect of hetero-deformation-induced (HDI) strengthening in Ni-Cu heterostructures can be tuned. The density of the Ni/Cu interface is tuned by adding Cu with different volume fractions to obtain the best combination of strength and plasticity. Compared with the previous HSs, the hardness differences between different regions of Ni-Cu HSs are more significant, and they are all composed of single substances. The hard Ni domain and the soft Cu domain are not only different in phase composition but also different in grain size. More interestingly, the density of the hard/soft domains can be adjusted independently, which provides a new way to explore the strength and plasticity balance of HS materials. The yield strength of Ni-Cu HS materials first increases and then decreases gradually with the increase in the Cu volume fraction. When the Cu volume fraction is less than 30%, the HDI strengthening effect in the Ni-Cu HS material can offset the effect of the yield strength reduction caused by Cu; with a further increase in the Cu volume fraction, the HDI strengthening effect is less than the yield strength reduction effect brought on by Cu.