Influence of interface shape on microstructure and mechanical properties of Mg/Al composite plates fabricated by hot-pressing

Abstract

A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface, which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate. The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate, which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing. In addition, the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing, which has a large effect on the texture components of the substrates near the corrugated interface. The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong “mechanical gearing” effect. Moreover, the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.

1. Introduction

In the past few years, the use of lightweight and high-strength laminated metal composites (LMCs) has surged due to the expanding new energy vehicle market and the increasing demand for high-thrust spacecraft in the aerospace industry [1,2]. Multi-layer composite materials like Ti/Al [3], Ti/Mg [4], Al/Cu [5] and Mg/Al [6,7] etc., have been developed. Among these, the Mg/Al LMCs have garnered significant attention [6−8]. Mg and its alloys boast high specific stiffness, specific strength and exceptional damping performance as the lightest structural metal materials [9−12]. Conversely, Al and its alloys demonstrate excellent corrosion resistance and remarkable plastic formability [13,14]. Therefore, Mg/Al LMCs are anticipated to amalgamate the strengths of Mg alloys and Al alloys, thus widening their potential applications.

Mg/Al LMCs have been produced through various methods such as composite casting [15,16], explosive welding [17−19], diffusion bonding [20−22], and plastic processing bonding (e.g., hot-pressing [23,24], hot extrusion [25−30] and hot rolling [2,31−34]), etc. It is reported that achieving strong interface bonding for Mg/Al LMCs may be challenging due to their different physical and chemical properties [35,36]. The interface bonding strength comes mainly from two sources, i.e., metallurgical bonding and mechanical bonding [37]. Metallurgical bonding strength can be influenced by controlling the compositions and thickness of the diffusion layer [37]. For Mg/Al LMCs, the brittle Mg−Al intermetallic compounds are easy to form at the interface, which will largely deteriorate bonding strength [37]. The addition of an intermediate layer (e.g., zinc foil, silver foil, nickel foil and copper foil) at the Mg/Al interface can effectively change the structures and compositions of the diffusion layer and is proven to be highly effective in strengthening the metallurgical bonding [20,38−40]. Besides, the mechanical bonding strength can also be enhanced by tailoring the interface shapes. Explosive welding and CFR (corrugated roll/flat roll rolling + flat roll/flat roll rolling) roll-bonding can generate a corrugated interface in the Mg/Al LMCs [41]. Moreover, WANG et al [42] fabricated Al/Mg/Al LMCs with a trapezoidal-shaped interface by pre-wire cutting and subsequent multi-pass hot rolling.