Study On Thermal Deformation Behavior Of 6061 Aluminum Matrix Composites Reinforced With Graphene

As a popular high-strength and lightweight material,aluminum matrix composites have high specific modulus,specific strength,good electrical and thermal conductivity,corrosion resistance and tensile strength,and are important materials in aerospace and automotive fields.The hot workability of aluminum matrix composites has been changed due to the addition of reinforcements,so it is of great significance to study the hot deformation behavior of composites.In this paper,the hot deformation behavior of 0.5%copper plated graphene reinforced 6061 aluminum matrix composite was studied,and its hyperbolic sine constitutive equation and hot working diagram were constructed to deeply understand the hot deformation behavior of aluminum matrix composite.The graphene and 6061 aluminum powder after electroless copper plating were sintered by vacuum hot pressing using powder metallurgy technology,and the test samples were obtained after heat treatment.Then,the MMS-200thermal simulation machine was used to conduct isothermal thermal simulation experiments on the samples.The experimental temperatures were300℃,350℃,400℃and 450℃respectively;The strain rates are 0.001 s^-1,0.01 s^-1,0.1 s^-1 and 1 s^-1 respectively.Data such as stress,strain rate,strain,temperature and time are obtained.According to the obtained experimental data,the rheological stress curve of the composite was analyzed.It was found that the rheological stress of the composite was proportional to temperature and inversely proportional to strain rate;The hyperbolic sine constitutive equation with strain parameters for 0.5%copper plated graphene reinforced6061 aluminum matrix composite was established,and its accuracy reached98.2%.According to DMM dynamic material model theory and Prasad instability criterion,the hot working diagram of 0.5%copper plated graphene reinforced6061 aluminum matrix composite was established,and the optimal processing parameter range under the experimental conditions was determined.The optimal processing parameter range was temperature 300℃-320℃,strain rate0.001s^-1-0.005s^-1,temperature 430℃-450℃,strain rate 0.5s^-1-1s^-1Through the metallographic images,it is found that during the hot compression process,when the deformation condition is high temperature and low strain rate,the internal structure of the material appears wedge-shaped cracking;At high temperature and moderate strain rate,recrystallization is incomplete and recrystallization grains are small;At high temperature and high strain rate,the nucleation rate of recrystallized crystal nucleus is higher and recrystallization is incomplete.