Extrusion and heat treatment characteristics of 35% SiCp/6061Al composites

Aiqinwang ,Jingpeixie ,Huidanguo ,Wenyanwang

doi:10.1680/jemmr.15.00062

Abstract

Silicon carbide particle (SiCp)-reinforced 6061 aluminum (SiCp/6061Al) composites were produced by vacuum hot-press sintering technology and were subjected to hot extrusion and T6 treatment. The microstructures of the composite materials were characterized by scanning electron microscopy and transmission electron microscopy. The density, tensile strength, hardness and conductivity of the composite materials were determined. The effects of hot extrusion and solution temperature on the microstructures and properties of SiCp/6061Al composites were investigated. The results show that hot extrusion can improve the microstructures and properties of the composite materials. After hot extrusion, the compact density improved from 98·09 to 99·10%, while the tensile strength was enhanced from 270 to 301 MPa. The properties of the composite materials can be further improved after T6 treatment. With increase in solution temperature, the dissolvable phases gradually mix and dissolve completely, with only a small quantity of insoluble phase remaining in the matrix, the hardness and tensile strength of composites first increase and then decrease, and the electrical conductivity decreases initially and attains stability after some time. After the solid is dissolved at 530°C and subjected to aging, the comprehensive property of SiCp/6061Al composite improves significantly. The tensile strength reaches 336 MPa, and the hardness is 101 HB.

Highlights

Silicon carbide particle (SiCp)-reinforced aluminum (Al) matrix composites have become attractive candidates as advanced structural materials for applications in the aerospace and military industries due to their desirable properties, including high specific stiffness, high specific strength, good fatigue and wear resistance.[1,2,3] There are various factors that affect the microstructure and mechanical properties of particle-reinforced aluminum matrix composites, such as the size, shape and volume fraction of the reinforced particle, the composition and grain size of matrix alloy and the preparation technology.[4]
For SiCp/aluminum 6061 (6061Al) composites, heat treatment is an effective method for enhancing the tensile strength and hardness, eliminate the residual stress of the interface, and can significantly improve the physical and mechanical properties of the composites
The research of Bo5 showed that the addition of SiCp cannot change the solid solution and the aging process of heat-treatable aluminum alloy matrix, but can change the technological parameters of the solid solution and the aging process of the composite

Summary

Introduction

Silicon carbide particle (SiCp)-reinforced aluminum (Al) matrix composites have become attractive candidates as advanced structural materials for applications in the aerospace and military industries due to their desirable properties, including high specific stiffness, high specific strength, good fatigue and wear resistance.[1,2,3] There are various factors that affect the microstructure and mechanical properties of particle-reinforced aluminum matrix composites, such as the size, shape and volume fraction of the reinforced particle, the composition and grain size of matrix alloy and the preparation technology.[4] Defects such as cavity and porosity appear in the matrix and the interface between the matrix and reinforcement during the process of vacuum hot-press sintering. 35 vol.% SiCp/6061Al composites were prepared by the vacuum hot-press sintering process and subjected to hot extrusion and T6 treatment, the effects of hot extrusion and heat treatment on the microstructure, mechanical properties and electrical conductivity of the composites were investigated

Experimental process

Results and analysis

Conclusion