Tensile properties and microstructure of 2024 aluminum alloy subjected to the high magnetic field and external stress

In order to explore the dependence of plasticity of metallic material on a high magnetic held,the effects of the different magnetic induction intensities(H = 0 T,0.5 T,1 T,3 T,and 5 T) and pulses number(N = 0,10,20,30,40,and 50) on tensile strength(σ_b) and elongation(δ) of 2024 aluminum alloy are investigated in the synchronous presences of a high magnetic held and external stress.The results show that the magnetic held exerts apparent and positive effects on the tensile properties of the alloy.Especially under the optimized condition of H~*=1 T and N~*=30,the σ_b and 8 are 410 MPa and 17% that are enhanced by 9.3% and 30.8% respectively in comparison to those of the untreated sample.The synchronous increases of tensile properties are attributed to the magneto-plasticity effect on a quantum scale.That is,the magnetic held will accelerate the state conversion of radical pair generated between the dislocation and obstacles from singlet to the triplet state.The bonding energy between them is meanwhile lowered and the moving flexibility of dislocations will be enhanced.At H~* = 1 T and N~* = 30,the dislocation density is enhanced by 1.28 times.The relevant minimum grain size is 266.1 nm,which is reduced by 35.2%.The grain rehning is attributed to the dislocation accumulation and subsequent dynamic recrystallization.The(211) and(220) peak intensities are weakened.It is deduced that together with the recrystallization,the hne grains will transfer towards the slip plane and contribute to the slipping deformation.     

强磁与应力场耦合作用下AZ31镁合金塑性变形行为

研究强磁场对AZ31镁合金塑变能力和微观组织的作用,在3 T脉冲强磁场条件下对合金进行磁场耦合应力时的拉伸实验.采用电子背散射衍射、Ⅹ射线衍射和透射电镜分析等方法研究材料的微观组织.结果表明:与0 T拉伸试样相比,3 T拉伸试样抗拉强度和延伸率分别提高了2.2%和28.7%,说明将强磁场耦合作用于材料塑性变形过程时,能在不降低材料强度的同时提高镁合金的塑性变形能力,有助于同步改善材料强韧性.磁场作用机理主要表现为磁致塑性效应,计算表明主要合金相β(Mg_(17)Al_(12))为顺磁性,有助于发挥磁场作用效果.磁场提高了位错运动灵活性并促使位错增殖,晶界处位错堆积和应力集中促进了再结晶形成,晶粒发生细化,发挥细晶强韧化效果;同时磁场诱发塑性变形时的晶粒转动,新生成非基面取向的晶粒弱化了镁合金(0001)基面织构,该组织特征有助于提高材料的塑变能力.