汽车发动机用铸造铝合金中新型纳米带析出沉淀相的形成机理及其对高温力学性能的影响

项目名称： 汽车发动机用铸造铝合金中新型纳米带析出沉淀相的形成机理及其对高温力学性能的影响

项目编号： No.51271209

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 贾志宏

作者单位： 重庆大学

项目金额： 80万元

中文摘要： 当前汽车全铝发动机主要是以Al-Si-Mg和Al-Si-Cu为基础的铸造合金材料。在工作温度高于200oC后合金中的Mg2Si或Al2Cu亚稳态沉淀强化相不稳定，逐渐失去其强化功效，导致合金材料服役寿命缩短。本项目将系统研究Al-Si-Mg(Cu)-Hf合金中一种高温稳定的Si-Hf纳米带沉淀强化相。应用先进微观分析表征技术（SEM，HRTEM，HAADF，in-situ TEM等）定量表征纳米带沉淀相的成分、晶体结构、尺寸、分布以及与Al基体的位向关系，分析沉淀相与各种结构缺陷的相互作用，考察微合金化溶质原子和沉淀相在微观结构形成过程中的作用；在上述基础上，重点揭示Si-Hf沉淀相的形成长大机理、强韧化机理及其对合金高温力学性能（强度、蠕变和疲劳）的影响。研究结果一方面将深入认识一种新型纳米带沉淀相，同时也为设计和开发新一代汽车发动机用耐高温铝合金材料提供理论指导和技术支持。

中文关键词： 铸造铝合金；析出相；生长机理；力学性能；微观表征

英文摘要： Automotive aluminum engine is mainly manufactured by the Al-Si-Mg and Al-Si-Cu-based casting alloys. When the operating temperature over 200oC the precipitation hardening metastable phases of Mg2Si or Al2Cu in the alloys become unstable and gradually lose their strengthening efficacy, resulting in shortened service life of the material. This project aims to systematically study one type of high temperature stable Si-Hf precipitation strengthening phase which has nanobelt-like morphology in the Al-Si-Mg (Cu)-Hf alloy. The research works in this proposal include: 1) to quantitatively characterize the precipitation phase composition, crystal structure, size, distribution, and its relationship with the Al matrix by using advanced micro-analytical characterization techniques (SEM, HRTEM, HAADF, in-situ TEM, etc.); 2) to analysis interactions between the precipitate phase and a variety of structural defects; 3) to examine the role of solute atoms of micro-alloying element and the precipitates in the microstructure formation process. Based on the above, we expect to reveal the formation and growth mechanism, strengthening and toughening mechanism of the Si-Hf precipitates, and its effect on high temperature mechanical performance (strength, creep and fatigue). Research results enable us to deeply understand a new type

英文关键词： As-cast Al alloy；precipitates；growth mechanism；mechanical property；Microstructural characterization