【摘要】 用Hopkinson杆实验装置在不同温度下对LY12铝合金进行动态压缩实验.采用XRD线形分析对压缩试样的微细观结构演化进行研究.由XRD的积分宽度确定试样中位错为刃型位错.衍射峰形的Fourier分析表明,在动态加载下,材料内部的位错密度在塑性流动的初期迅速趋于饱和,且随着测试温发的升高,位错密度呈递减趋势,同时亚结构的尺寸不断增加.衍射峰形分析结果显示在280—300℃之间亚结构尺寸迅速增长,与LY12铝合金在280℃附近发生第:相粒子的溶解对应.更多还原

【Abstract】 The plastic deformation of metals under dynamic loading is related to the evolution of dislocation structure and density which is thermal activation-dependent.The dynamic compressive experiment on LY12 aluminum alloy has been performed by Hopkinson bar at different temperatures. X-ray diffraction line profile analysis is adopted for the tested specimens to investigate the micro-and/or meso-scale structure evolution.The edge character of dislocations in the specimens was determined by analyzing the integral breadths of X-ray diffraction lines.The Fourier analysis of diffraction lines indicates that under dynamic loading,the dislocation density approaches to saturation rapidly at the initial stage of plastic deformation,dislocations are homogeneously distributed in the specimens.It also demonstrates that the dislocation density decreases with increasing testing temperature. Meanwhile the size of substructures has a tendency of broadening with temperature,especially in the range from 280℃to 300℃which corresponds to the temperature of dissolution of precipitated phase in the aluminum matrix.更多还原