电磁搅拌对Al_2O_(3p)/ZL109复合材料组织与性能的影响

Effects of Electromagnetic Stirring on Microstructure and Properties of In-Situα-Al_2O_(3p)/ZL109 Composites for Pistons

采用半固态机械搅拌法,结合电磁搅拌技术成功制备了α-Al_2O_(3p)体积分数为5%的ZL109复合材料,研究了电磁搅拌对α-Al_2O_3颗粒分散性、力学性能及布氏硬度的影响,并测定了复合材料的线性热膨胀系数。结果表明,在电流为250A、频率为5Hz、磁感应强度为0.039T、时间为10 min的工艺条件下,α-Al_2O_3增强颗粒取得最佳的分散效果,基本无团聚。经T6热处理后,复合材料的抗拉强度和(HB)硬度为325 MPa和148,与基体相比,分别提高了10.2%和18.4%;因硬质α-Al_2O_3颗粒的引入,伸长率(2.7%)下降了20.6%。在30~400℃区间,复合材料的线性热膨胀系数值均低于ZL109基体合金。在30℃和400℃,复合材料的线性热膨胀系数与ZL109合金相比,分别降低了7.97%和3.79%。

5%Al2O3p/ZL109composites were fabricated successfully by semi-solid mechanical stirring with aid of electromagnetic stirring technology in A1/SiO2system.The effects of electromagnetic stirring on the dispersion ofα-Al2O3particles,tensile property and Brinell hardness of the composites were investigated.And the linear thermal expansion coefficient（LTEC）of ZL109and composites were also tested.The results reveal thatα-Al2O3particles present the desirable dispersion effect with current of250A,frequency of 5Hz,magnetic induction intensity of 0.039Tfor 10min,and agglomeration phenomenon can be ignored.Tensile strength and Brinell hardness of T6-treated composites reach 325MPa and 148HB,increased by 10.2%and 18.4%,respectively,compared with those of the matrix alloy.Because of the introduction of hardα-Al2O3particles,the elongation（2.7%）of composite is decreased by20.6%compared with that of ZL109 matrix alloy.At 30-400℃,the LTEC values of the composites are lower than those of ZL109.At 30℃and 400℃,the LTEC values of composites are decreased by7.97%and 3.79%compared with those of ZL109,respectively.