Fabrication of 7075-0.25Sc-0.15Zr Alloy with Excellent Damping and Mechanical Properties by FSP and T6 Treatment
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JMEPEG https://doi.org/10.1007/s11665-018-3451-2
Fabrication of 7075-0.25Sc-0.15Zr Alloy with Excellent Damping and Mechanical Properties by FSP and T6 Treatment Y.F. Mo, C.Y. Liu, G.B. Teng, H.J. Jiang, Y. Chen, Z.X. Yang, Y. Chen, and S.C. Han (Submitted November 30, 2017; in revised form March 7, 2018) This study investigated the effects of Sc and Zr additions, friction stir processing (FSP), and subsequent solid solution and artificial aging (T6) treatment on the microstructure, damping capacity, and mechanical properties of 7075 Al alloy. The minor Sc and Zr additions promoted the grain refinement of this alloy during FSP and inhibited the growth of fine equiaxed grains in the FSP sample during subsequent T6 treatment. Thus, the fine equiaxed grain structure and high density of the g¢ precipitated phase were simultaneously obtained in the 7075 Al alloy containing Sc and Zr after FSP and T6 treatment, and this sample exhibited superior mechanical properties and damping capacity to those of the 7075 Al alloy after T6 treatment. This work provides an effective strategy for preparing Al alloys with excellent damping capacity and mechanical properties. Keywords
Al alloy, damping capacity, mechanical properties, microstructure
1. Introduction Damping capacity is a measure of the ability to dissipate elastic strain energy during mechanical vibration or wave propagation. The development and application of high-damping materials can effectively improve the reliability and service life of the component parts. 7075 Al alloy is one of the major types of ultimate high-strength alloys and is widely employed as a structural material in aircraft and other transportation applications, because of its high strength-to-weight ratio performance (Ref 1). However, commercial Al alloys, including 7xxx Al alloys, are regarded as low-damping materials. Thus, improvement in the damping capacity of 7075 alloy is desirable to extend its engineering applications. In our previous investigation, it was found that friction stir processing (FSP) can fabricate Al alloys with fine equiaxed grain structure, and this structure could effectively improve the damping capacity of Al alloys (Ref 2, 3). However, heat is generated from severe friction between the rotation tool and the workpiece during FSP, and the maximum temperature in the stirred zone usually reaches as much as 480 C (Ref 4). Such high temperature leads to the precipitation of g phase, which corresponds to the over-aging state of the 7xxx Al alloys, thereby causing the deterioration of the mechanical properties of Al alloys (Ref 2). Artificial aging after solid solution (T6) treatment leads to the precipitation of g¢ phase and then
Y.F. Mo, Alnan Aluminium Co., Ltd., Nanning 530031, China; C.Y. Liu, G.B. Teng, H.J. Jiang, Y. Chen, Z.X. Yang, Y. Chen, and S.C. Han, Key Laboratory of New Processing Technology for Nonferrous Metal and Materials, Ministry of Education, Guilin University of Technology, Guilin 541004, China. Contact e-mail: [email protected].
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