热处理对石墨烯镁基复合材料拉伸性能及微结构的影响

Effect of heat treatment on tensile properties and micro-structure of graphene-magnesium matrix composites

为研究时效对石墨烯纳米片/镁基复合材料(GNPs/AZ31)力学性能的影响,对GNPs/AZ31进行了300℃固溶1 h和200℃分别时效4、8、12、16、20、24 h的热处理,并开展不同时效时间下的GNPs/AZ31微观组织表征与拉伸力学性能试验研究。单轴拉伸力学试验发现,随着时效时间的增加,GNPs/AZ31的力学性能呈现出先增加后减小的趋势,在时效时间为20 h时的综合力学性能最好,抗拉强度、屈服强度、延伸率、断裂功和显微硬度分别为381 MPa、258 MPa、23.7%、76 J/m^(3)和75.7 HV,比未处理的GNPs/AZ31复合材料分别提高了9.5%、4.5%、13.9%、24.6%和37.6%。微结构表征试验结果表明,随着时效时间的增加,GNPs/AZ31内第二相(Mg_(17)Al_(12))的析出数量明显增加,并且时效过程均以增加粒径小于1.0μm的小尺寸颗粒的连续析出为主;XRD图谱显示,随着时效时间的增加,Mg_(17)Al_(12)相衍射峰强度得到加强,GNPs/AZ31的(0002)基面织构强度得到提高。本研究可为改善GNPs/AZ31的综合力学性能提供重要的试验数据。

To study the effect of aging on the mechanical properties of graphene nanoplatelets/magnesium matrix composites(GNPs/AZ31),GNPs/AZ31 were subjected to solid solution heat treatment at 300℃for 1 h and 200℃for 4,8,12,16,20 and 24 h,respectively,and the microstructure characterization and tensile properties tests of GNPs/AZ31 at different aging time were carried out.The uniaxial tensile mechanical tests revealed that the mechanical properties of GNPs/AZ31 showed a trend of increasing and then decreasing with the increase of aging time,and the best overall mechanical properties were obtained at 20 h of aging,with tensile strength,yield strength,elongation,fracture work and microhardness of 381 MPa,258 MPa,23.7%,76 J/m^(3)and 75.7 HV,respectively,which compared with those of the untreated GNPs/AZ31 composites increased by 9.5%,4.5%,13.9%,24.6%and 37.6%,respectively.The results of microstructural characterization tests showed that the number of precipitated second phase(Mg17Al12)within GNPs/AZ31 increased significantly with increasing aging time,and the aging processes were all dominated by increasing the continuous precipitation of small-sized particles<1.0μm.XRD patterns showed that the intensity of Mg_(17)Al_(12)phase diffraction peaks was enhanced with increasing aging time;The intensity of the(0002)basal texture of GNPs/AZ31 was improved with increasing aging time.This study can provide important experimental data for improving the comprehensive mechanical properties of GNPs/AZ31.