Abstract
The in situ SiC/Al composites were fabricated in Al-Si-C systems with different Si/C mass ratios and holding time by the method of combustion synthesis and hot press consolidation. The influences of Si/C mass ratio and holding time on the phase constitution, microstructure, and hardness of the composites were investigated. The results indicate that the increase of Si/C mass ratio leads to more uniform size distribution of the SiC particles in the Al matrix. Moreover, by improving the Si/C mass ratio from 4 : 1 to 5 : 1, the maximum size of SiC particle was reduced from 4.1 μm to 2.0 μm. Meanwhile, the percentage of submicroparticles was increased from 22% to 63%, and the average hardness value of the composites was increased by 13%. In addition, when the holding time is set to be fifteen minutes, the Al4C3 phase did not exist in the composites because of its total reactions with Si atoms to form SiC particles, and the average hardness value was 73.8 HB.
Highlights
The SiC reinforced aluminum matrix (SiC/Al) composites have become very promising materials in the fields of semiconductor packaging, automobile, and aeronautics industry due to their high thermal conductivity and low coefficient of thermal expansion, lightweight, high strength, and wearresistance [1,2,3,4,5]
Cracks could appear in the interfaces due to the formation of thin oxide layers on the surfaces of the particles. To overcome these drawbacks stated above, the research on Al matrix composites is moving in two directions: one is metallic glasses replaced by typical ceramic particles reinforcements [20,21,22]; the other is in situ methods replaced by traditional ex situ methods
The in situ SiC/Al composite was firstly fabricated in an Al-Si-C system with the Si/C mass ratio of 5 : 1 at 950∘C and holding time for 15 min
Summary
The SiC reinforced aluminum matrix (SiC/Al) composites have become very promising materials in the fields of semiconductor packaging, automobile, and aeronautics industry due to their high thermal conductivity and low coefficient of thermal expansion, lightweight, high strength, and wearresistance [1,2,3,4,5]. Several methods have been applied to fabricate the SiC/Al composites, such as stir casting [10,11,12], hot pressing sintering [2, 13], powder metallurgy [8], liquid pressing process [14], high pressure solidification [15], and squeeze-cast [16]. In these methods the reinforcing SiC particles are usually directly added to Al matrix to form ex situ SiC/Al composites. To overcome these drawbacks stated above, the research on Al matrix composites is moving in two directions: one is metallic glasses replaced by typical ceramic particles reinforcements [20,21,22]; the other is in situ methods replaced by traditional ex situ methods
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