直接熔化制备Al-Si-Al_(2)O_(3)复合材料的组织和性能

Microstructure and Properties of Al-Si-Al_(2)O_(3) Composites Prepared by Direct Melting

采用光学显微、XRD、SEM和EDS分析了Si含量分别为10.00wt%、7.64wt%的Al-Si-Al_(2)O_(3)复合材料的显微组织形貌以及物相组成。结果表明:Al-10.00wt%Si试样的组织细小,孔隙率较高。基体晶粒Al呈细小圆形,Si颗粒主要在基体晶界周围聚集长大,部分向基体晶粒内部生长;而Al-7.64wt%Si试样组织略微粗大,孔隙率较低。基体晶粒Al呈不规则形状,Si颗粒聚集长大现象更为明显。原位反应成功进行,Al-10.00wt%Si复合材料以Al为基体生成的Al_(2)O_(3)是增强相;另一生成物Si没有细小弥散的分布于Al基体中,而是聚集附着在基体Al晶界周围,且有部分SiO_(2)残留存在于基体晶界周围。在加热升温过程中,混合原料只出现了部分熔化现象,金属液滴从混合原料中析出,凝结为含Al量极高的合金液滴。合金液滴致密度较高,固溶体呈枝晶状,Si呈条状或针状;且有小颗粒第二相的存在,含有Al、Si、C元素。

The microstructure and phase composition of Al-Si-Al_(2)O_(3) composite with Si content of 10.00wt%,7.64wt%were analyzed by optical microscopy,XRD,SEM and phase analysis.The results show that the microstructure of the Al-10.00wt%Si sample is fine and the porosity is high.The grain Al of the matrix is fine and round,and the Si particles mainly aggregate and grow around the grain boundary of the matrix,and partly grow into the grain interior of the matrix.However,the microstructure of Al-7.64wt%Si sample is slightly coarse and the porosity is low.The grain Al of matrix is irregular,the phenomenon of Si grain aggregation is more obvious.The in situ reaction is carried out successfully,the Al_(2)O_(3) of the Al-10.00wt%Si composite formed by the Al matrix is the reinforced phase.The other lifetime Si does not distribute in the Al matrix,but aggregates around the grain boundary,and some SiO2 remains around the grain boundary of the matrix.During the heating and heating process,the mixed raw materials only generate partial melting phenomenon,the metal droplets precipitate from the mixed raw materials and condense into alloy droplets with extremely high Al content.The alloy droplet density is high,solid solution is dendrite,Si is stripe or needle,and there are small particles of the second phase,containing Al,Si and C elements.