Microstructure and mechanical behavior of functionally graded Al A359/SiCp composite
Microstructure and mechanical behavior of functionally graded Al A359/SiCp composite
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DOI：
10.1016/s0921-5093(01)01400-9
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发表时间：
2002-01
期刊：
影响因子：
6.4
通讯作者：
R. Rodríguez-Castro;R. C. Wetherhold;M. H. Keleştemur
中科院分区：
文献类型：
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作者：
R. Rodríguez-Castro;R. C. Wetherhold;M. H. Keleştemur
研究了离心铸造Al-A359/SiCp功能梯度复合材料的组织和力学行为，包括拉伸和断裂性能。采用离心浇注的方法，使颗粒体积分数和弹性模数沿一定方向以连续的形式逐渐变化。通过对不同碳化硅含量的拉伸试件的拉伸试验，研究了碳化硅颗粒增强对A359铝合金强化的影响。在0.20-0.30范围内，随着碳化硅体积分数的增加，材料的抗拉强度和屈服强度不断提高。相反，当碳化硅浓度在0.30-0.40范围内时，抗拉强度和屈服强度降低。骨折实验按ASTM E399标准进行。对矩形Al/SiCp块材的单边裂纹板拉伸(SECT)和单边裂纹四点弯曲(4PB)试件进行了断裂试验。用MTS810型伺服液压机和日立S-800型扫描电子显微镜分别测定了材料的断裂韧性、断裂韧度和断口形貌特征。在较高的碳化硅浓度(较低的裂纹长度)下，裂纹尖端基质的塑性变形限制了能量的耗散，从而产生较低的断裂韧性值。相反，裂纹长度越长，碳化硅含量越少，吸收的能量越多，断裂韧性值越高。复合材料的断裂过程为孔洞结合型断裂，但随着碳化硅含量的增加，孔洞尺寸变小。此外，扫描电子显微镜断口还表明，碳化硅的断裂和解聚以颗粒断裂为主，且随着颗粒浓度的增加，断裂发生率增加。
The microstructure and mechanical behavior including tensile and fracture properties of a functionally gradient Al A359/SiCpcomposite processed by centrifugal casting have been investigated. The particle volume fraction and, therefore, elasticity modulus was gradually changed in the continuous form along a certain direction by using the centrifugal casting. The effect of SiC particulate reinforcement on strengthening of A359 Al alloy was experimentally studied by tensile testing specimens with different SiC contents. There was a continuous increase in tensile and yield strength with increasing SiC volume fractions in the range of 0.20–0.30. On the contrary, there was a reduction in tensile and yield strength for SiC concentrations in the range of 0.30–0.40. The fracture experiments were performed according to the ASTM E399 standards. Single edge cracked plate tension (SECT) and single edge cracked four point bending (4PB) specimens, which are taken from rectangular Al/SiCpblocks, were used for fracture tests. The fracture toughness, KIC, and fractographic characteristics of the material were determined by using MTS 810 servohydraulic machine and Hitachi S-800 scanning electron microscopy (SEM), respectively. At elevated SiC concentrations (low values of crack length), limited dissipation of energy by restrained plastic deformation of the matrix at the crack tip produced low fracture toughness values. On the contrary, at longer crack lengths SiC content decreased and there was more absorption of energy, resulting in higher fracture toughness values. A ductile failure process of void coalescence type fracture in the matrix of the composite was observed but the void size was less when the SiC concentration was higher. In addition, SEM fractographs also displayed that fracture and de-cohesion of SiC occurred with particle fracture dominating over de-cohesion and with fracture incidence increasing as particle concentration increases.