Microstructure and properties of high-fraction graphite nanoflakes/6061Al matrix composites fabricated via spark plasma sintering
(1. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;
2. Electric Power Research Institute, State Grid Anhui Electric Power Co., Ltd., Hefei 230601, China;
3. Anhui Province Key Laboratory of Microsystem, Hefei 230088, China;
4. Hefei Shengda Electronic Technology Industry Co., Ltd., Hefei 230088, China;
5. Engineering Research Center of High Performance Copper Alloy Materials and Processing, Ministry of Education, Hefei 230009, China)
2. Electric Power Research Institute, State Grid Anhui Electric Power Co., Ltd., Hefei 230601, China;
3. Anhui Province Key Laboratory of Microsystem, Hefei 230088, China;
4. Hefei Shengda Electronic Technology Industry Co., Ltd., Hefei 230088, China;
5. Engineering Research Center of High Performance Copper Alloy Materials and Processing, Ministry of Education, Hefei 230009, China)
Abstract: 30–50？wt.% graphite nanoflakes (GNFs)/6061Al matrix composites were fabricated via spark plasma sintering (SPS) at 610？°C. The effects of the sintering pressure and GNF content on the microstructure and properties of the composites were investigated. The results indicated that interfacial reactions were inhibited during SPS because no Al4C3 was detected. Moreover, the agglomeration of the GNFs increased, and the distribution orientation of the GNFs decreased with increasing the GNF content. The relative density, bending strength, and coefficient of thermal expansion (CTE) of the composites decreased, while the thermal conductivity (TC) in the X-Y direction increased. As the sintering pressure increased, the GNFs deagglomerated and were distributed preferentially in the X-Y direction, which increased the relative density, bending strength and TC, and decreased the CTE of the composites. The 50wt.%GNFs/6061Al matrix composite sintered at 610？°C under 55？MPa demonstrated the best performance, i.e., bending strength of 72？MPa, TC and CTE (RT-100？°C) of 254？W/(m·K) and 8.5×10-6？K-1 in the X-Y direction, and 55？W/(m·K) and 9.7×10-6？K-1 in the Z direction, respectively.
Key words: electronic packaging composite; spark plasma sintering (SPS); 6061Al alloy; graphite nanoflake (GNF); microstructure; thermal property; mechanical property