【作者】 权燕燕；

【导师】 彭晓东；

【作者基本信息】 重庆大学 ， 材料加工工程， 2005， 硕士

【摘要】 本文研究了塑性变形对Al-Fe 原位增强铝基复合材料显微组织及力学性能的影响。采用机械搅拌法制备的Al-Fe 原位增强铝基复合材料中,增强相Al3Fe 以较大的长条状分布在铝基体上,大大降低了该材料的综合力学性能,对材料进行热处理后,增强相分布均匀性得到一定改善,然而晶粒还是比较粗大。本文就是基于上述情况来研究的,主要采用等通道转角挤压(Equal Channel Angular Pressing,简称ECAP)、压缩变形这两种塑性变形来研究纯铝、铝基复合材料的晶粒细化规律。首先研究了该复合材料的基体材料—工业纯铝的ECAP 塑性变形工艺,获得挤压路径、挤压次数对其显微组织和力学性能的影响规律,从而得出ECAP 变形工艺的最佳工艺参数,这对铝基复合材料ECAP 研究有很大的参考价值。在ECAP 工艺对Al-Fe 原位增强铝基复合材料的变形试验过程中,复合材料发生断裂,其主要原因如下: (1) 该复合材料本身脆性较强,受限塑性变形能力较差;(2) 材料的熔炼过程控制不当导致材料有很多缺陷;(3) 实验中采用的液压机无法控制挤压速度,挤压过快。采用压缩变形工艺对Al-Fe 原位增强铝基复合材料进行了变形试验研究,结果表明:压缩速度和压缩变形量对Al-Fe 原位增强铝基复合材料的显微组织有重要影响,长条状Al3Fe 相经历破碎、钝化、扭曲、细化、均匀化等过程,最终形成细小的颗粒状组织;压缩变形大大改善了复合材料的增强相的分布均匀性;经压缩变形后,复合材料的破坏机理由脆性断裂向塑性断裂转变。更多还原

【Abstract】 The effect of the plastic deformation on the microstructure and mechanical property of aluminum matrix composites reinforced by Al-Fe intermetallics was researched in this paper. The composites was prepared by technique of mechanical stirring, the strip-like of intensifying phase of Al3Fe distributed in the aluminum, obviously, the general mechanical property was sharply lowered. After the heat treatment, the uniformity of the distribution of intensifying phase was mended, but the size of the crystal grain still thick as before. Therefore, in order to refine the grain of intensifying phase and heightened the mechanical property of the material, the other ways should be adopted. The two ways of plastic deformation, equal channel angular pressing (ECAP) and compressing deformation, were used in this paper for those purpose. Firstly, the law of plastic deformation of commercially pure aluminum was researched in this paper. Three different routes of press were used in the experiment of ECAP of aluminum, and then, the effects of pressing routes and pressing times on the microstructure and mechanical property of aluminum were analyzed, a best technology was summarized, and there was a great value of reference for the research of the aluminum matrix composites in ECAP. Secondly, the experiment of plastic deformation of the composites was carried out with two ways of compression deformation and ECAP. The composites were broken during the experiment of ECAP. The reasons of this fracture were analyzed in the paper, there were three chief reasons, (1) brittleness of this composites was high; (2) there were many flaws in the material by the bad control in the course of smelting; (3) the pressing velocity of the hydrostatic press was too fast, because it could not be controlled. In the experiment of compressing deformation, with different velocities of compressing, the sample of these composites was deformed at different degree. Through the analysis of the effect of compressing velocity and the quantity of compressing deformation on the microstructure of composites, it was found that there was a series of fracture, passivating, warping, refining and uniformity of strip-like of Al3Fe in the course of compressing deformation of the sample, at the end, the strip-like microstructure was fractured and changed into exiguous grain-like microstructure. The result of hardness showed that the uniformity of the distribution of intensifying phase was greatly mended by compressing deformation. The different of fore-and-aft fracture were analyzed; it showed that after the deformation, the brittle fracture morphology before the deformation had been changed to plastic fracture morphology.更多还原