The effect of initial structures of Mg/Cu super-laminates on hydrogen absorption/desorption properties

•The effect of initial structures of Mg/Cu super-laminates on hydrogen absorption/desorption properties was investigated.•Three types of specimens were prepared in cold rolling. Each of them had a fine, medium, coarse microstructure, respectively.•Two types of MgCu2 forms, 3D-network and layered forms, were observed after hydrogenation.•Alloying with Mg and Cu, and hydrogenation of Mg are competitive processes.•The dominant process depends on the initial structures of Mg/Cu super-laminates.

The effect of initial structures of Mg/Cu super-laminates on hydrogen absorption/desorption properties was investigated experimentally. Mg/Cu super-laminates were prepared by a repetitive fold and roll method using a conventional two-high roll mill. Three types of specimens were prepared by changing rolling reduction in cold rolling. Each of them had a fine, medium, coarse microstructure, respectively. Hydrogen absorption/desorption properties were measured with HP-DSC and a Sieverts’ type instrument. Microstructures were observed with SEM. Two types of MgCu2 forms, 3D-network and layered forms, were observed after hydrogenation under the conditions of 573 K, 86.4 ks and 3.3 MPa of H2, respectively. This implies that Mg/Cu super-laminates can be hydrogenated by two kinds of processes. The dominant process depends on the initial structures of Mg/Cu super-laminates. Repetitive hydrogenation/dehydrogenation tests using HP-DSC indicate that, even after 20 cycles, the initial microstructures of Mg/Cu super-laminates can affect their hydrogen absorption/desorption properties.