对合成Al_3Ti/ADC12复合材料微观组织与力学性能的影响（英文）

Effect of Sr Modification on Microstructures and Mechanical Properties of Al_3Ti/ADC_(12) Composites

研究了不同含量的改性剂Sr对原位合成Al_3Ti/ADC12复合材料微观组织及力学性能的影响。通过光学显微镜以及扫描电镜观察复合材料的微观以及断口组织。结果表明:Sr的加入能有效减小α-Al以及Al_3Ti颗粒尺寸以及优化材料组织形态。Sr的最优加入量为0.25%(质量分数)。在该加入量条件下,共晶硅由针状或短棒状变为颗粒状,α-A1粗枝晶得到较好的细化,抗拉强度以及延伸率相对基体材料增加了36.9%和58%。断口形貌表明,在最优加入量条件下所制备的复合材料断口几乎看不到解理面和脆性平坦区,韧窝数量增多,韧窝尺寸变得更小且深,同时分布也较为均匀。断口形貌的特征与材料力学性能变化相一致。

The effects of Sr modification on the microstructure and properties of Al3Ti/ADC12 composite were investigated. The microstructures and fracture surfaces of the composite were examined by optical microscope and SEM. Results show that the addition of Sr reduces the sizes of the α-Al primary phase and Al3Ti particles and modifies the morphology of the composite. The optimum level of Sr content is 0.25 wt%, and the eutectic silicon changes from an acicular or short rod shape into a granule one. Coarse dendritic of the primary α-A1 phases is fully refined. Results also show that Sr addition leads to the improvement in mechanical properties. Compared with matrix alloys, the tensile strength and elongation of the composite are increased by 36.9% and 58%, respectively when the Sr addition is 0.25 wt%. Furthermore, fractographic examinations reveals that cleavage surfaces and brittle plain area could hardly be seen from the Al3Ti/ADC12 composite with addition of 0.25 wt% Sr. The dimples are increased in quantity and diminished in size, deeper and well-distributed. The fracture appearances match the tendency of the tensile properties.