Influence of Porosity on Mechanical Behavior of Porous Cu Fabricated via De-Alloying of Cu–Fe Alloy

We report on a study of the mechanical behavior of porous Cu containing micron-sized pores and fabricated by de-alloying of a Cu–Fe precursor alloy. Our results show that the minimum volume fraction of pores that can be obtained by using an approach that involves de-alloying of a Cu–Fe precursor alloy is approximately 40 vol%. Moreover, the average pore size formed by de-alloying Cu–Fe of varying compositions is in the range of 1.5–4.0 μm. Our mechanical behavior results reveal that the yield stress increases from 3.9 to 58.6 MPa as the volume fraction of porosity decreases from 78.9% to 39.3%. Moreover, our data shows that the influence of porosity on the relative yield stress and relative Young’s modulus conforms to the scaling equations of Gibson and Ashby as formulated for open-cell porous metals. The pore cell characteristics and deformation modes of porous Cu produced by de-alloying Cu–Fe alloys were discussed in the context of the observed fluctuations in the value of the constants C and n in the Gibson-Ashby scaling equation. The evolution of microstructure during compressive deformation of porous Cu was studied and the results reveal an increase in the fraction of low-angle grain boundaries, an increase in the number of twins and a decrease in the average grain size with increasing strain from 0% to 70%.