Fabrication and Mechanical Behavior of High-Porosity Bulk Bimodal Porous Cu Via Chemical De-alloying of Cu-Al Alloys

Abstract

A novel method to fabricate bulk bimodal porous Cu by chemical de-alloying the Cu-Al precursor alloys was reported in this paper, and the effects of microstructure on their mechanical behaviors were studied. Three Cu-Al precursor alloys, Cu30Al70, Cu20Al80 and Cu10Al90, were fabricated by arc-melting, and then, the bulk bimodal porous Cu was obtained by de-alloying the precursors in 20 wt.% NaOH solution at 65 °C. The phase composition and microstructure of both the precursor alloys and as-de-alloyed bulk bimodal porous Cu were studied utilizing x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray spectrometry. Furthermore, the compressive strength of bulk bimodal porous metals was tested to study the relationship between microstructure and mechanical properties. The bimodal porous Cu (with large pores of 1-5 μm and fine pores of 30-150 nm) exhibits a porosity increase from 73.9 to 90.8%, a compressive strength decrease from 1.53 to 0.15 MPa and a unit energy absorption decrease from 0.28 to 0.08 MJ/m3. Our result shows that the phase composition and distribution of the precursor alloys directly influence the microstructure of the bulk bimodal porous Cu. And the correlation between microstructure and mechanical behavior of bulk bimodal porous Cu was discussed.