脉冲电磁场效应对2195铝锂合金力学性能的影响及机理

Effects and mechanism of pulsed electromagnetic field effect on mechanical properties of 2195 Al-Li alloy

基于试样不发生形变的脉冲电磁场效应实验装置,研究了脉冲电磁场效应对应变量为0.09的退火变形态2195铝锂合金力学性能和微观组织的影响规律及机理。发现脉冲电磁场效应对材料维氏硬度呈现阶梯影响规律。当放电电压低于临界电压(13 kV)时,试样的维氏硬度随放电电压的增加而降低,相对退火变形态试样降低达8.1%,脉冲电磁场对试样产生软化效应。当放电电压高于临界电压时,脉冲电磁场的软化效应与硬化效应趋于动态平衡。通过微观组织表征,发现脉冲电磁场效应可以促进材料第二相溶解,其平均尺寸和面积分数分别相对退火变形态试样降低8.8%和13.9%;脉冲电磁场效应影响材料位错演变,脉冲电磁场效应使得材料位错密度从退火变形态试样的2.37×10^(14)m^(-2)降低至1.42×10^(14)m^(-2)。此外,阐明了脉冲电磁场效应下材料软化和硬化现象的来源及机理,揭示了涡流软化效应和磁致应力硬化效应对位错、第二相及维氏硬度演变的影响机理。

Based on the pulsed electromagnetic field experimental device which restrain the specimen from deforming,the effect laws and mechanism of pulsed electromagnetic field on mechanical properties and microstructure of deformed annealed 2195 Al-Li alloy with the pre-strain of 0.09 was studied.It is found that the pulsed electromagnetic field has a straircase effect on the Vickers hardness of the material.When the discharge voltage is lower than the critical voltage(13 kV),the Vickers hardness of the material decreases with the increase of discharge voltage,and the relative decrease reaches 8.1%compared with the deformed annealed specimen.The pulsed electromagnetic field presents softening effect on the specimens.When the discharge voltage is higher than the critical voltage,the softening effect and hardening effect of pulsed electromagnetic field tend to be dynamically balanced.Through microstructure characterization,it is found that the pulsed electromagnetic field effect can promote the dissolution of the second phase,and its average size and area fraction are decrease by 8.8%and 13.9%compared with the deformed annealed specimen,respectively.The pulsed electromagnetic field effect affects the dislocation evolution of materials.The dislocation density decreases from 2.37×10^(14)m^(-2) of the deformed annealed specimen to 1.42×10^(14)m^(-2).In addition,the origin and mechanism of softening and hardening phenomena of materials under pulsed electromagnetic field effect were explained.The effects mechanism of eddy current softening effect and magnetically induced stress hardening effect on dislocation,the second phase and Vickers hardness evolution was revealed.