摘要
在脉冲强磁场(2T、3T和4T)中对固态纳米Al_2O_3颗粒增强Al-Zn-Mg-Cu基复合材料进行磁场处理,研究了磁场处理对复合材料的残余应力和拉伸性能的影响,并分析了强化机制。结果表明:在磁场强度B为3T时残余应力达到最小值(-1 MPa),比磁场处理前初始态试样的残余应力降低了102.4%。外加磁场降低了位错密集区和稀疏区间的长程应力。在B=4T时材料的质量因数比磁场处理前初始态试样提高12.7%,位错密度的提高有助于发挥位错强化机制;在磁场的作用下合金的析出相以非稳态η′(MgZn_2)相为主,有助于材料强韧性的提高。基于第一性原理计算了在磁场作用下MgZn_2相成键过程中的自旋态密度,为η′相的析出提供了理论依据。在B=2T时材料拉伸断口的特征主要表现为韧性断裂,对应较高的延伸率9.3%,比磁场处理前的初始态试样提高了12%。
Nanometer sized Al_2O_3 reinforced Al-Zn-Mg-Cu matrix composites were subjected to treatments in high pulsed magnetic field with different magnetic induced intensity 2T, 3T and 4T. The results demonstrate that the residual stress arrives to a minimum of-1MPa by an applied 3T pulsed magnetic field, which decreased by 102.4% compared to that of the original composite. The applied magnetic field can relax the long range distance stresses between areas with dense and sparse dislocations respectively; Meanwhile, the magnetic field increases the mobility of dislocations and accelerate the release velocity of internal stress, then the residual stress is, thereafter, lowered. The tensile strength increased with the enhancement of magnetic induced intensity. By 4T magnetic field the introduced mass factor, which is a combined parameter to represent the tensile strength and elongation, was enhanced by 12.7% compared to that of the original composite. The high dislocation density is beneficial to the dislocation induced strengthening. Besides, an other important reason lies in that the applied magnetic field may facilitate the formation of metastable η＇（MgZn_2） phase as the main precipitates, which somewhat substitute the common η（MgZn_2） phase. Thereby, the increase of η＇（MgZn_2） can improve the strength and toughness of composites. Furthermore,based on the first principle the density of electron spin state is calculated, which corresponds to the bonds formation process. By 2T magnetic field treatment, the fractograph of the composite exhibits the characteristic of ductile fracture that corresponds to a higher elongation of9.3%, which is 12% higher than that of the original composite.
作者
李桂荣
王芳芳
郑瑞
王宏明
黄超
薛飞
朱弋
LI Guirong WANG Fangfang ZHENG Rui WANG Hongming HUANG Chao XUE Fei ZHU Yi(School of Materials Science ＆ Engineering, Jiangsu University, Zhenjiang 212013, China)
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2016年第10期745-752,共8页
Chinese Journal of Materials Research
基金
国家自然科学基金51371091
51001054
51174099
江苏大学大学生实践创新训练项目~~
关键词
铝基复合材料
脉冲强磁场
残余应力
拉伸性能
aluminum matrix composite
pulsed high magnetic field
residual stress
tensile property
