原位颗粒对近液相线铸造6063铝合金微观组织和耐磨性的影响机理

Influence mechanism of in-situ particles on microstructure and wear resistance of 6063 aluminum alloy cast by near liquidus

摘要:

以CuO-Al作为反应体系,在6063铝合金中原位反应生成Al₂O₃颗粒,采用近液线相铸造的方法制备6063Al-XAl₂O₃(X=0,2,4,6)复合材料。研究原位反应颗粒Al₂O₃与6063铝合金自带的原位结晶颗粒Mg₂Si的形状、尺寸、数量、分布、界面特征等对合金微观组织和耐磨性的影响机理。结果表明,在6063铝合金中原位反应生成尺寸在亚微米级的近球形θ-Al₂O₃颗粒；其(311)晶面与6063铝合金基体(111)晶面成共格界面；6063铝合金中Mg₂Si尺寸大约为100nm,呈条带状,其(02-2)与Al基体(111)晶面属于共格界面。随着Al₂O₃颗粒含量的增加,6063铝基复合材料的晶粒组织形貌由蔷薇状逐渐向等轴晶转变,晶粒尺寸逐渐减小。当Al₂O₃的质量分数为6%时,复合材料组织由等轴晶和细小的柱状晶组成。载荷为50N时,6063铝合金的磨损量为6.72mg,6063-6Al₂O₃复合材料的磨损量为1.63mg,相对于6063铝合金降低75.7%。原位颗粒(Al₂O₃+Mg₂Si)与铝基体都成共格界面,界面之间无污染,界面结合强度高,在磨损过程中,不易从基体中脱落,承当磨损过程中的大部分载荷。原位生成高硬度的Al₂O₃颗粒与原位结晶颗粒Mg₂Si协同作用共同提高复合材料的耐磨性。外加载荷为40N时,随着增强相质量分数的增加,复合材料的磨损机制由粘着磨损转变为磨粒磨损。6063铝合金磨损机制以严重的粘着磨损为主。6063-2Al₂O₃复合材料磨损机制主要以粘着磨损为主,6063-4 Al₂O₃和6063-6Al₂O₃复合材料主要表现为磨粒磨损。

Abstract:

_{: The 6063Al-xAl2O3 (X= 0,2,4,6) composite was prepared by the method of near liquid line casting using CuO-Al as the reaction system to form Al2O3 particles in the in-situ reaction of 6063 aluminum alloy. The influence mechanism of the shape, size, quantity, distribution and interface characteristics of in-situ reaction particle Al2O3 and in-situ crystallization particle Mg2Si of 6063 aluminum alloy on the microstructure and wear resistance of the alloy was studied. The results show that near spherical θ-Al2O3 particles with sub-micron size are formed in the in-situ reaction of 6063 aluminum alloy. The (311) crystal plane has a coherent interface with the (111) crystal plane of 6063 aluminum alloy matrix. The size of Mg2Si in 6063 aluminum alloy is about 100nm, which is banded, and its (02-2) crystal faces with Al matrix (111) belong to coherent interface. With the increase of the content of Al2O3 particles, the grain morphology of 6063 Al matrix composites changes from rose-like to equiaxed grain gradually, and the grain size decreases gradually. When the mass fraction of Al2O3 is 6%, the microstructure of the composite is composed of equiaxed grains and fine columnar grains. When the load is 50N, the wear of 6063 aluminum alloy is 6.72mg, and the wear of 6063-6Al2O3 composite is 1.63mg, which is 75.7% lower than that of 6063 aluminum alloy. The in-situ particles (Al2O3+Mg2Si) form a coherent interface with the aluminum matrix. There is no pollution between the interfaces and the interface bonding strength is high. In the wear process, it is not easy to fall off from the matrix and bear most of the load in the wear process. The synergistic effect of in-situ formation of high hardness Al2O3 particles and in-situ crystalline particles Mg2Si can improve the wear resistance of composites. When the applied load is 40N, the wear mechanism of the composites changes from adhesion wear to abrasive wear with the increase of the mass fraction of reinforcement phase. The wear mechanism of 6063 aluminum alloy is mainly serious adhesion wear. The wear mechanism of 6063-2Al2O3 composites is mainly adhesive wear, and the wear of 6063-4Al2O3 and 6063-6Al2O3 composites is mainly abrasive wear.}