This study investigated the effects of silicon and silicon carbide particles contents on the thermal, hardness and microstructural behaviour of Al-Si-SiCp composites. 16 samples of the composite produced by stir casti...This study investigated the effects of silicon and silicon carbide particles contents on the thermal, hardness and microstructural behaviour of Al-Si-SiCp composites. 16 samples of the composite produced by stir casting technique were of silicon contents of 1, 2, 3 and 4% by weigh, and silicon carbide contents of 0.5, 1, 1.5 and 2% by weight for each composition of silicon. Each of the samples were subjected to homogenizing annealing heat treatment. Differential thermal analysis (DTA), hardness test and microstructural analysis were then performed on the samples from each composition. The results obtained showed that the hardness of the composite increased gradually as the silicon and silicon carbide particles content increased. The micrographs obtained revealed the presence of silicon carbide, silicon precipitates and aluminium carbide (Al4C3) within the metallic matrix. The amounts of these phases varied with the silicon and silicon carbide content. All the samples gave DTA curves with major endothermic peaks between 550 – 570℃ and two sets of exothermic peaks between 580 – 610℃ for the first set and between 565 – 570℃ for the second set. It was inferred from the study that although varied silicon and silicon carbide contents affected the thermal, hardness and microstructural behaviour of the Al-Si-SiCp composites, the variation of the SiCp content had a more pronounced effect on the hardness value of the Al-Si-SiCp composite.展开更多
采用喷射沉积法制备15%(体积分数)4.5 m SiCp/Al-20Si复合材料及其基体合金,研究该组材料的微观组织、力学性能、高周疲劳性能以及疲劳断口形貌。结果表明:SiC颗粒的加入有利于提高材料的力学性能;复合材料及其基体的高调疲劳寿命随应...采用喷射沉积法制备15%(体积分数)4.5 m SiCp/Al-20Si复合材料及其基体合金,研究该组材料的微观组织、力学性能、高周疲劳性能以及疲劳断口形貌。结果表明:SiC颗粒的加入有利于提高材料的力学性能;复合材料及其基体的高调疲劳寿命随应力幅值的减小而增加,在相同应力幅值下,复合材料的疲劳寿命远远高于基体合金。疲劳裂纹从大颗粒的初晶Si的断裂以及Si相脱离处形核,并开始扩展。对于复合材料而言,SiC颗粒尺寸较小,不容易发生断裂,在形核过程中,当裂纹遇到SiC颗粒时,裂纹或者避开增强体,或者受阻于SiC颗粒,只能在基体合金中扩展,从而扩大了疲劳形核区的面积,提高了材料的疲劳寿命。Si颗粒的脱离、Si相的断裂以及SiC颗粒与基体界面的脱粘是复合材料疲劳断裂失效的主要机制。展开更多
文摘This study investigated the effects of silicon and silicon carbide particles contents on the thermal, hardness and microstructural behaviour of Al-Si-SiCp composites. 16 samples of the composite produced by stir casting technique were of silicon contents of 1, 2, 3 and 4% by weigh, and silicon carbide contents of 0.5, 1, 1.5 and 2% by weight for each composition of silicon. Each of the samples were subjected to homogenizing annealing heat treatment. Differential thermal analysis (DTA), hardness test and microstructural analysis were then performed on the samples from each composition. The results obtained showed that the hardness of the composite increased gradually as the silicon and silicon carbide particles content increased. The micrographs obtained revealed the presence of silicon carbide, silicon precipitates and aluminium carbide (Al4C3) within the metallic matrix. The amounts of these phases varied with the silicon and silicon carbide content. All the samples gave DTA curves with major endothermic peaks between 550 – 570℃ and two sets of exothermic peaks between 580 – 610℃ for the first set and between 565 – 570℃ for the second set. It was inferred from the study that although varied silicon and silicon carbide contents affected the thermal, hardness and microstructural behaviour of the Al-Si-SiCp composites, the variation of the SiCp content had a more pronounced effect on the hardness value of the Al-Si-SiCp composite.
文摘采用喷射沉积法制备15%(体积分数)4.5 m SiCp/Al-20Si复合材料及其基体合金,研究该组材料的微观组织、力学性能、高周疲劳性能以及疲劳断口形貌。结果表明:SiC颗粒的加入有利于提高材料的力学性能;复合材料及其基体的高调疲劳寿命随应力幅值的减小而增加,在相同应力幅值下,复合材料的疲劳寿命远远高于基体合金。疲劳裂纹从大颗粒的初晶Si的断裂以及Si相脱离处形核,并开始扩展。对于复合材料而言,SiC颗粒尺寸较小,不容易发生断裂,在形核过程中,当裂纹遇到SiC颗粒时,裂纹或者避开增强体,或者受阻于SiC颗粒,只能在基体合金中扩展,从而扩大了疲劳形核区的面积,提高了材料的疲劳寿命。Si颗粒的脱离、Si相的断裂以及SiC颗粒与基体界面的脱粘是复合材料疲劳断裂失效的主要机制。
