简介概要

喷射沉积AlFeVSi合金热暴露过程中相转变与沉积态组织特点

来源期刊:中南大学学报(自然科学版)2007年第5期

论文作者:肖于德 钟掘 黎文献 马正青

文章页码:795 - 795

关键词:喷射沉积;快速凝固;铝合金;相变

Key words:spray deposition; rapid solidification; aluminum alloy; phase transformation

摘    要:采用喷射沉积工艺制备快速凝固AlFeVSi合金薄片和沉积管坯,通过示差热分析、X射线衍射分析、金相显微组织观察、透射电镜组织观察、硬度测试等检测手段,研究了喷射沉积AlFeVSi合金快凝薄片在高温热暴露过程中的相变和组织演变规律,并分析了喷射沉积AlFeVSi合金坯组织特点。结果表明,喷射沉积AlFeVSi快凝薄片基本上为呈微胞状的过饱和α-Al固溶体。加热温度低于500 ℃时,在高温热暴露过程中微胞状结构发生分解,α-Al过饱和固溶体脱溶,形成α-Al+Al12(Fe,V)3Si (bcc,a≈1.260 nm) 弥散颗粒的分解产物,当温度高于500 ℃时,Al12(Fe,V)3Si颗粒粗化聚集,并以独立形核长大的方式生成θ-Al13Fe4块状相。随着热暴露温度升高,喷射沉积AlFeVSi合金薄片的硬度呈下降趋势。喷射沉积AlFeVSi坯主要由α-Al固溶体和Al12(Fe,V)3Si颗粒组成,但也存在少量含粗大片状或块状相的非快速凝固组织。

Abstract: The rapidly solidified flake and pipe blank of spray deposited AlFeVSi aluminum alloy were prepared through the multi-layer spray deposition process in the atomization medium of nitrogen gas. Phase transformation and microstructural evolution of the as-deposited flakes during thermal exposure at high temperature were studied by means of differential thermal analysis (DTA), X-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM) and hardness measurement, and microstructures of the spray deposited billet of the Al-8.5Fe-1.3V-1.7Si aluminum alloy were characterized. The results show that the rapidly solidified flakes of AlFeVSi alloy mainly consist of α-Al supersaturated solid solution with microcellular structure. During thermal exposure below 500 ℃, the microcellular structure decomposes, and the α-Al supersaturated solid solution transforms into the mixture of Al12(Fe,V)3Si particles dispersed in α-Al matrix,while above 500 a℃ the Al12(Fe,V)3Si particles coarsen and congregate, and even form lumpish θ-Al13Fe4 phase in an independently nucleating and growing mode. With the increase of exposure temperature, hardness of the rapidly solidified flake of spray deposited AlFeVSi aluminum alloy exhibits obvious reducing trend. The spray deposited billet of the Al-8.5Fe-1.3V-1.7Si aluminum alloy consists on the whole of two phase mixture of α-Al and Al12(Fe,V)3Si (bcc, a≈1.260 nm), which is characterized generally as the fine Al12(Fe,V)3Si particles dispersed uniformly in the α-Al matrix, but there appears a very small amount of non-rapidly solidified microstructures with coarse lumpish particles of θ-Al13Fe4 phase in the condition of near rapid solidification or slowly solidification.

基金信息:国家重点基础研究发展规划项目
中国博士后科学基金资助项目



详情信息展示

喷射沉积AlFeVSi合金热暴露过程中相转变与沉积态组织特点

肖于德1, 2,钟  掘2,黎文献1,马正青1

(1. 中南大学 材料科学与工程学院,湖南 长沙,410083;

2. 中南大学 机电工程学院,湖南 长沙,410083)

摘  要:采用喷射沉积工艺制备快速凝固AlFeVSi合金薄片和沉积管坯,通过示差热分析、X射线衍射分析、金相显微组织观察、透射电镜组织观察、硬度测试等检测手段,研究了喷射沉积AlFeVSi合金快凝薄片在高温热暴露过程中的相变和组织演变规律,并分析了喷射沉积AlFeVSi合金坯组织特点。结果表明,喷射沉积AlFeVSi快凝薄片基本上为呈微胞状的过饱和α-Al固溶体。加热温度低于500 ℃时,在高温热暴露过程中微胞状结构发生分解,α-Al过饱和固溶体脱溶,形成α-Al+Al12(Fe,V)3Si (bcc,a≈1.260 nm) 弥散颗粒的分解产物,当温度高于500 ℃时,Al12(Fe,V)3Si颗粒粗化聚集,并以独立形核长大的方式生成θ-Al13Fe4块状相。随着热暴露温度升高,喷射沉积AlFeVSi合金薄片的硬度呈下降趋势。喷射沉积AlFeVSi坯主要由α-Al固溶体和Al12(Fe,V)3Si颗粒组成,但也存在少量含粗大片状或块状相的非快速凝固组织。

关键词:喷射沉积;快速凝固;铝合金;相变

中图分类号:TG146.2         文献标识码:A         文章编号:1672-7207(2007)05-0795-07

Phase transformation during thermal exposure and microstructural characteristics of spray deposited billets of AlFeVSi aluminum alloy

XIAO Yu-de 1, 2, ZHONG Jue 2, LI Wen-xian 1, MA Zheng-qing 1

(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;

2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China)

Abstract: The rapidly solidified flake and pipe blank of spray deposited AlFeVSi aluminum alloy were prepared through the multi-layer spray deposition process in the atomization medium of nitrogen gas. Phase transformation and microstructural evolution of the as-deposited flakes during thermal exposure at high temperature were studied by means of differential thermal analysis (DTA), X-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM) and hardness measurement, and microstructures of the spray deposited billet of the Al-8.5Fe-1.3V-1.7Si aluminum alloy were characterized. The results show that the rapidly solidified flakes of AlFeVSi alloy mainly consist of α-Al supersaturated solid solution with microcellular structure. During thermal exposure below 500 ℃, the microcellular structure decomposes, and the α-Al supersaturated solid solution transforms into the mixture of Al12(Fe,V)3Si particles dispersed in α-Al matrix,while above 500 a℃ the Al12(Fe,V)3Si particles coarsen and congregate, and even form lumpish θ-Al13Fe4 phase in an independently nucleating and growing mode. With the increase of exposure temperature, hardness of the rapidly solidified flake of spray deposited AlFeVSi aluminum alloy exhibits obvious reducing trend. The spray deposited billet of the Al-8.5Fe-1.3V-1.7Si aluminum alloy consists on the whole of two phase mixture of α-Al and Al12(Fe,V)3Si (bcc, a≈1.260 nm), which is characterized generally as the fine Al12(Fe,V)3Si particles dispersed uniformly in the α-Al matrix, but there appears a very small amount of non-rapidly solidified microstructures with coarse lumpish particles of θ-Al13Fe4 phase in the condition of near rapid solidification or slowly solidification.

Key words: spray deposition; rapid solidification; aluminum alloy; phase transformation

快速凝固AlFeVSi合金热加工成型后的理想组织可以概述为:晶粒为亚微米量级α-Al过饱和固溶体基体上均匀分布着高达16%~36%(体积分数)的纳米级金属间化合物Al12(Fe,V)3Si[1-3]。事实上,快凝AlFeVSi合金的力学性能、耐热性能和高温服役寿命在很大程度上取决于这种α-Al+Al12(Fe,V)3Si两相组织的粗细、均匀性和热稳定性[1-6]。因此,了解快速凝固AlFeVSi合金在热/力作用下的相变和组织演变规律对其最终成型材料组织性能控制尤为重要。

喷射沉积作为一种集快速凝固、半固态加工和近终形加工于一体的新型材料制备技术,近些年来也被用于制备快速凝固耐热铝合金[6-8]。过去的研究工作表明[8-11],高温加热时,快速凝固AlFeVSi合金雾化粉末或平面流铸造薄带中的亚稳组织会朝着平衡化方向转变,主要表现为:过饱和固溶体脱溶,Al12(Fe,V)3Si颗粒粗化、聚集,以及发生向θ-Al13Fe4平衡相转化的有害相变。然而,喷射沉积AlFeVSi合金坯组织状态与雾化粉末或平面流铸造薄带的相比存在差异,这导致在它们后续加热或热加工过程中的相变和组织演变规律也存在差异[12-13]

本文作者对喷射沉积AlFeVSi合金快凝薄片在高温热暴露过程中的相变和组织演变规律进行研究,同时结合这种演变规律分析喷射沉积坯的显微组织特点,旨在为研制高性能喷射沉积Al-Fe-V-Si合金大规格制品提供有益的参考依据。

1  试验方案与过程

喷射沉积AlFeVSi合金坯在中南大学自制喷射沉积设备上制备,其原理如图1所示。采用高压氮气雾化,调节雾化喷嘴往返平移、沉积基底转动和垂直下降来控制喷嘴和沉积基底的相对距离和运动,制取不同形状和规格的沉积坯[12-13]。沉积旋转轴空心通水,降低沉积温度而提高冷却速率。

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