简介概要

High temperature deformation behavior andmechanism of spray deposited Al-Fe-V-Si alloy

来源期刊:中国有色金属学报(英文版)2007年第6期

论文作者:肖于德 王伟 黎文献

文章页码:1175 - 1180

Key words:spray deposition; heat-resistant aluminum alloy; constitutive equation; high temperature plastic deformation; stress exponent; activation energy; dislocation detachment

Abstract: Al-8.5Fe-1.3V-1.7Si alloy was prepared by spray deposition and hot extrusion. The high temperature plastic deformation behavior of the spray deposited Al-8.5Fe-1.3V-1.7Si alloy was investigated in the strain rate range of 2.77×10-4-2.77×10-2 s-1 and temperature range of 350-550 ℃ by Gleebe-1500 thermomechanical simulator. The mechanism of the high temperature plastic deformation of the alloys was studied by TEM associated with the analysis of Rosler-Artz physical constitutive relationship based on the model of dislocation detaching from dispersion particles. The results show that Al-Fe-V-Si alloy has low strain hardening coefficient, and even exhibits work softening. Stress exponent n and activation energy Q were calculated based on Zener-Hollomon relation and Rosler-Artz physical model respectively. The Rosler-Artz physical model can give a good prediction for the abnormal behavior of high temperature deformation of spray deposited Al-Fe-V-Si alloy, that is, n larger than 8 and Q higher than 142 kJ/mol. However, because of the highly refined microstructure, the high temperature deformation behavior of spray deposited Al-Fe-V-Si alloy deviates more or less from the law predicted by using Rosler-Artz physical model.



详情信息展示

High temperature deformation behavior and mechanism of

spray deposited Al-Fe-V-Si alloy

XIAO Yu-de(肖于德), WANG Wei(王 伟), LI Wen-xian(黎文献)

School of Materials Science and Engineering, Central South University, Changsha 410083, China

Received 15 July 2007; accepted 10 September 2007

                                                                                                

Abstract: Al-8.5Fe-1.3V-1.7Si alloy was prepared by spray deposition and hot extrusion. The high temperature plastic deformation behavior of the spray deposited Al-8.5Fe-1.3V-1.7Si alloy was investigated in the strain rate range of 2.77×10-4-2.77×10-2 s-1 and temperature range of 350-550 ℃ by Gleebe-1500 thermomechanical simulator. The mechanism of the high temperature plastic deformation of the alloys was studied by TEM associated with the analysis of Rosler-Artz physical constitutive relationship based on the model of dislocation detaching from dispersion particles. The results show that Al-Fe-V-Si alloy has low strain hardening coefficient, and even exhibits work softening. Stress exponent n and activation energy Q were calculated based on Zener-Hollomon relation and Rosler-Artz physical model respectively. The Rosler-Artz physical model can give a good prediction for the abnormal behavior of high temperature deformation of spray deposited Al-Fe-V-Si alloy, that is, n larger than 8 and Q higher than 142 kJ/mol. However, because of the highly refined microstructure, the high temperature deformation behavior of spray deposited Al-Fe-V-Si alloy deviates more or less from the law predicted by using Rosler-Artz physical model.

Key words: spray deposition; heat-resistant aluminum alloy; constitutive equation; high temperature plastic deformation; stress exponent; activation energy; dislocation detachment

                                                                                                               

1 Introduction

Rapidly solidified Al-Fe-V-Si heat resistance aluminum alloy is a kind of light-mass structural materials with high specific strength, high specific stiffness and good heat-resistance[1-5]. It is able to be applied in the temperature range of 150-350 ℃ (and even higher temperature) to replace some of titanium alloys or steels, meeting the needs of advanced space shuttle, aircrafts and missiles to achieve high flying velocity and large carrying capacity in the modern space-flight and aviation industries[6-8]. Spray deposition technique can be used to develop large-scale structural materials of the rapidly solidified Al-Fe-V-Si alloy, substituting for the rapid solidification-powder metallurgical process.

Spray deposited Al-Fe-V-Si alloy should be hot worked at high temperature (400-500 ℃) and used in the temperature range from 150 ℃ to 350 ℃[9-12]. Consequently, it is important to understand the high temperature deformation behavior and mechanism of the spray deposited Al-Fe-V-Si alloy. A number of models regarding to the high temperature deformation behavior and mechanism, such as Ansell-Weertman model, critical stress model and Rosler-Artz physical model, have been discussed recently[13-20]. Ansell-Weertman reported that dislocation can climb the dispersed particles or loop the particles according to Orowan mechanism, as a result, the size of the dispersed particles influenced the creep process directly. In critical stress model, MISHA et al[20-21] reported that the creep behavior of dispersed alloys can be describe by

                (1)

where  C is a material constant, σ0 the critical stress, λ the mean particle space, b the length of Burgers vector, DL the coefficient of volume self-diffusion, DL=DL0?  exp(-QL/RT), QL the activation energy of crystal diffusion of aluminum alloy, QL≈142 kJ/mol. CARRENO and RUANO[22] utilized this model to describe the creep behavior of rapidly solidified Al-Fe-V-Si alloy. However, the model was unable to give a proper interpretation about the facts that its stress exponent value is much larger than 8, and activation energy larger than 142 kJ/mol.

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