Superplastic behavior of Al-coated Mg alloy sheet

• Published in: Journal of alloys and compounds 2014-07, Vol.601, p.179-185
• Main Authors: Tokunaga, Toko, Matsuura, Kiyotaka, Ohno, Munekazu
• Format: Article
• Language: English
• Subjects: Cladding; Composite material; Condensed matter: structure, mechanical and thermal properties; Deformation and plasticity (including yield, ductility, and superplasticity); Diffusion; interface formation; Exact sciences and technology; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Mechanical property; Mg alloy; Physics; Solid surfaces and solid-solid interfaces; Superplasticity; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.02.099

•Al-coated Mg alloy plates were successfully fabricated into sheets by hot forging.•The Al-coated Mg alloy sheets exhibited a large elongation of 550 %.•The Al coating perfectly remained on the substrate after such large elongation.•The elongation of Al coating is attributable to the uniform Mg alloy deformation. An Al-coated Mg alloy sheet is fabricated by hot forging an Al-coated Mg alloy plate produced by hot extrusion of a Mg alloy billet together with an Al plate. The sheet consists of recrystallized fine grains both in the Mg alloy substrate and Al coating layer. A thin intermetallic compound layer of Al3Mg2 formed at the Al/Mg interface in the hot-extruded plate. The subsequent hot forging reduces the thickness of the intermetallic layer but induces cracks in the intermetallic compound. This sheet exhibits a large tensile elongation of 550% at 573K and at a strain rate of 1.0×10−3s−1. Notably, a tensile test of an Al specimen exhibited only 40% elongation, while that of a Mg alloy specimen exhibited 800% elongation. It is suggested that the large elongation of Al as the coating layer on the Mg alloy is attributable to the good bonding of the Al coating layer and the Mg alloy substrate. The cracks in the intermetallic layer disappear during the tensile tests at elevated temperatures and no cracks are observed in the elongated specimens, which indicates growth of the intermetallic and reparation of the cracks occurred during the low strain-rate hot deformation of the Al-coated Mg alloy sheet.