Fe_3Al基合金用作结构材料的应用基础研究  

RESEARCH OF Fe_3AI INTERMETALLICS IN APPLICATION TO STRVCTURAL MATERIAL

作　　者：孙祖庆[1] 高德春[2] 杨玉珥 黄晓旭[1] 黄继华[2] 

机构地区：[1]北京科技大学新金属材料国家重点实验室 [2]北京科技大学

出　　处：《材料研究学报》2001年第1期69-76,共8页Chinese Journal of Materials Research

基　　金：八六三计划新材料领域资助项目!863-715-005-0121

摘　　要：研究了 Ｆｅ—２８Ａｌ－５Ｃｒ与 Ｆｅ—２８Ａｌ－５Ｃｒ—０．５Ｎｂ—０．１Ｃ合金的高温变形行为，发现温度在 ８５０ ℃左右，应变速率为 ８．３３Ｘ１０－４ｓ－１时，呈现出大晶粒的超塑性变形行为，延伸率分别达到 １４５％ 和２５４％．这意味着不需要获得细晶的特别工艺处理就可以直接进行超塑性成形，与传统细晶导致超塑性 不同，其激活能分别为 ２４３ｋＪ／ｍｏｌ和 ２１８ｋＪ／ｍｏｌ，变形机理为位错运动而不是品界滑动，在较低的应 变速率及大约 ８５０ ℃下制备出壁厚为 １．７～２ｍｍ，直径为 ５０ｍｍ的薄壁管坯　分别用电子束焊（ＥＢＷ） 及钨极氩弧焊（ＧＴＡ）两种方法对厚度为 ２ｍｍ左右的 Ｆｅ－Ａｌ基合金试样进行了可焊性及焊接工艺优化 研究电子束焊在真空中进行，集中的高能量输入使熔合区组织细化，可实现对 Ｆｅ３ＡＩ基合金的焊接　采 用钨极氩弧焊时，以中低碳铬钼钢为填充料，降低焊接电流和热输入，对焊件采用适当的预热、缓冷工艺， 是焊接工艺优化的主要因素，应用可焊性及焊接工艺优化研究的结果。Superplastic deformation behavior in coarse-grained Fe-28Al-5Cr and Fe-28A- 5Cr0.5Nb-0.1C alloys has been examined at a given initial strain rate of 8.33 x 10-4s-1 and the temperature of 850 ℃. Large elongation was achieved in both alloys. A maximum of 145% was obtained in Fe 28AI-5Cr alloy. and it is 254% obtained in Fe-28Al-5Cr-0.5Nb-0.1C alloy. This indicates that the present intermetallic alloys could be processed at high temperature without special effort to obtain a fine-grained structure. The deformation activation energy was determined to be about 243kJ/mol for Fe-28Al-5Cr alloy, and 218kJ/mol for Fe-28Al-5Cr-0.5Nb-0.1C alloy. which are different from that usually shown in fine-grained structures. This suggests that the related mechanism during the superplastic deformation of the present alloys is the movement of dislocations rather than the grain boundary sliding. The coiled thin wall pipe stock with a thickness of 1.7-2mm and diameter of 50 mm has been successfully made using a specially self-designed auxiliary assemble at lower strain and the temperature of 850 ℃ as an application of the research of superplastic deformation. The weldability and its process optimum of Fe-Al based alloys at a thickness of 2mm have been carried out by using electron beam (EB) welding and gas tungsten arc (GTA) welding respectively. Because of the highly focused beam, lower heat source. and vacuum environment, leading to a narrow weld zone, EB can successfully produce high quality welds of Fe3AI based intermetallic alloys. The most important welding parameters to optimize the processing are as follows : filler of medium carbon steel containing Cr and Mo, lower welding current and heat input, proper pre- and post-weld heat treatment. Based on these results. thin wall welding pipes have been successfully made.

关 键 词：超塑性 电子束焊 钨极氩弧焊 可焊性 铁铝基合金 结构材料 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG406[金属学及工艺—金属材料]