Short Communication Microstructure and property of the composite laminate cladded by explosive welding of CuAlMn shape memory alloy and QBe2 alloy S. Gong a,1 , Z. Li a,b, * , Z. Xiao a,1 , F. Zheng a,2 a School of Materials Science and Engineering, Central South University, 410083 Changsha, China b Key Laboratories of Nonferrous Metal Materials Science and Engineering, Ministry of Education, 410083 Changsha, China article info Article history: Received 17 March 2008 Accepted 25 June 2008 Available online 11 July 2008 abstract Microstructure and properties of the composite laminate cladded by explosive welding of CuAlMn and QBe2 alloy have been evaluated. The melting zone is almost encountered in full interface of the cladded materials. As it is aged at 350 °C for 20 min and at 430 °C for 5 min prior to solution-treatment at 770 °C for 3 min, the internal friction of the laminate is 16  10 3 below 125 °C and reaches a maximum of 28  10 3 at 140 °C. r 0.01 , r 0.2 and r b are 460 Mpa, 935 Mpa and 1087 Mpa, respectively. The fracture mechanism of the composite showed predominantly quasi-cleavage and cleavage modes. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction A perfect relay spring should possess excellent elastic property and damping capacity. The contactor can be either held tightly or ejected abruptly by the spring with excellent elastic capacity. How- ever, the spring of excellent damping capacity can be stopped quickly from the whipping state once being ejected or pushed down. The combining elastic and damping properties are required to improve the operation life and reliability of the relay. The high damping capacity is considered as one of the most important functional properties of shape memory alloys and can be used for energy absorbing and vibration damping applications [1–3]. Be-bronze has an excellent elastic capacity with electric conductivity. Explosive welding is a solid-state process in which controlled explosion forces to join two or more materials together under high pressures [4–6]. Its major industrial application lies in the fact that it can be used to clad dissimilar materials, many of which are impossible to join by any other methods [6–7]. A novel elasticity-damping composite laminate has been devel- oped by explosive welding of CuAlMn and QBe2 alloy. The project of the present work is to investigate the microstructure-property relationship for the cladding materials and study the fracture behavior of cladding plate. 2. Experimental methods The shape memory alloy Cu 73 Al 24 Mn 3 (at.%) was inducted melted, cast into flat ingots. The surface defects of the ingot were cut off prior to homogenization at 1123 k for 24 h and subse- quently hot-rolled to 1.5 mm thick strip at 1073 k. The strips were solution-treated at 1073 k for 10 min before water-quenching. The transformation temperatures were determined by q–T curve, where Ms was 220 °C and As was 210 °C. The QBe2 layer was re- ferred to as base plate while the shape memory alloy as Flyer, which were mechanical polished and cut into dimension of 300  250  3 mm and 300  250  1.5 mm, respectively. The EL- BAR 5 (ammonium nitrate 90%, min 4.5% fuel–oil and min 3.0% TNT) was chosen as explosive material. The detonation velocity of the explosive material was 2500–3000 ms 1 . The density of explosive material was 0.8 g cm 3 . The explosive rate and stand off distance of the flyer plate were 2 and 2t, respectively, prior to detonation. The parallel arrangement was used for experimental set-up for explosive welding as schematically shown in Fig. 1. The structure of the composite laminate was such that the QBe2 layer setting in the middle with the Cu-based shape memory alloy layers on both sides (the ratio of thickness of SMA/QBe2/SMA  1:2:1), man- ufactured by explosive welding twice. The composite laminate as explosive welding was hot rolled to 2 mm. In order to obtain the thermoelastic martensite in shape memory alloy and high strength in QBe2, the composite laminate was subjected to double aging at 350 for 20 min and 420 °C for 5 min prior to solution treatment at 770 °C for 3 min. The specimen was mechanically polished and followed by elec- tro-polished in a mixing solution of CH 3 CH 2 OH and H 3 PO 4 with a volume radio of 1:1. The metallographic examination of sample was carried out using metallographic microscope (Polyver–MET) 0261-3069/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.matdes.2008.06.067 * Corresponding author. Address: School of Materials Science and Engineering, Central South University, 410083 Changsha, China. Tel.: +86 731 8830264; fax: +86 731 8876692. E-mail addresses: ok.11@163.com (S. Gong), lizhou6931@gmail.com, lizhou6931@163.com (Z. Li), xiaozhu8417@gmail.com (Z. Xiao), fzheng@mail.csu. edu.cn (F. Zheng). 1 Tel.: +86 731 8830264; fax: +86 731 8876692. 2 Tel.: +86 731 8836948; fax: +86 731 8876692. Materials and Design 30 (2009) 1404–1408 Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes