循环应变波形对铝疲劳过程中超声衰减的影响

研究了高纯多晶铝在三角和正弦两种波形的应变控制下的疲劳过程中的超声衰减.结果表明，在小应变振幅下，影响超声衰减变化地主要是位错与点缺陷间的相互作用，波形的变化能改变点缺陷的分布，因而影响超声衰减的变化；而在大应变振幅下，位错大量增殖，对超声衰减变化起主导作用的是位错与位错间的相互作用，波形对位错增殖和位错间相互作用影响甚小. 关键词：

INFLUENCE OF THE CYCLIC STRAIN WAVEFORM ON THE ULTRASONIC ATTENUATION DURING THE FATIGUE PROCESS OF ALUMINIUM

The ultrasonic attenuation Δα has been measured during the fatigue process of aluminium which is controlled by the total strain with a triangular or a sinusoidal waveform.The results indicate that the waveform has an influence on the Δα-ε curve at low strain amplitude,but has little influence at high strain amplitude.At low strain amplitude,the major reason causing the variation of Δα is the interaction between dislocations and point defects,and the waveform can change the re-distribution of point defects at the average stress field of the vibrating dislocation segments,as a result,the stable Δα-ε curves for the two kinds of waveform are different.At high strain amplitude,dislocation multiplication occurs,the interaction between dislocation segments is dominant,and the waveform cannot influence the dislocation multiplication and the interaction between dislocation segments.