The Research On Preparation Of Al Matrix Composites By In Situ Reaction

This article was prepared by in situ synthesis of particle-reinforced aluminum matrix composites. The use of two different reactants, and the other is TiO₂ and B₂O₃ powder, and the other is KBF₄ and K₂TiF₆ powder, to prepare of in situ reaction of the particle reinforced composite materials in ZL102 alloy. Studied different process parameters to enhance the effects of particles , given satisfactory preparation process of particle reinforced aluminum matrix composites, and compared the two different reactants in the synthesis of composite materials to enhance particle morphology, the selection and formation thermodynamics of reinforcing phase,the relationship between matrix and reinforcing phase and reinforcing mechanism have been studied carefully. The microstructures, phase configurations and the distribution of the two-phase particle reinforced phase ZL102 in situ composite have been studied by means of analysis of TEM method. The hardness of the ZL102 composite have also been tested.The morphology of microstructure has been characterized by metallographic microscope,scanning electron microscope, X-ray Diffraction (XRD). The main results are as follows:(1) Experiments show that: by the reaction of TiO₂ and B₂O₃ powder were prepared in situ ZL102 composites ideal process parameters are as follows: reaction mixture by adding a green form, the amount of 15%, the reaction temperature is 900℃, the reaction time was 20 min, plus more large mixing intensity.(2) Experiment show that: by the reactant of KBF₄ and K₂TiF₆ powder were prepared in situ ZL102 composites ideal process parameters are as follows:accession can generated 1% TiB₂ the KBF₄ and K₂TiF₆ powder, the reaction temperature is 1000℃, the reaction time was 10 min.(3) The experimental results show that using of Al-TiO₂-B₂O₃ system can be prepared in situ (TiB₂+Al₂O₃) /ZL102 composite, the composite materials to increase hardness of 37.3% than the ZL102,using of KFB₄ and K₂TiF₆ prepared in situ (TiB₂ + Al₃Ti) / ZL102 composite hardness than the 60.3% raise ZL102.(4)Microstructure analysis shows that the grain size ofα-Al and eutectic Si of in situ composite is smaller than that of ZL102 matrix.(5)EPMA analysis shows that the shapes of TiB₂ is particle and rod,the shapes of Al₂O₃ is rock candy-like , the shapes of Al₃Ti is longer reinforcement bar ,The in-situ reinforcing phases are distributed uniformly in the matrix and the interface withα-Al is good combination, and they demonstrate remarkable grain-refining effect on the matrix.(6)The reinforcing mechanism for the in-situ composites is fine-grain reinforcing,dispersion reinforcing and dislocation reinforcing.