Microstructure and composition characteristics of transition zone in diffusion bonding of Fe3Al intermetallics to Q235 low carbon steel
(1. National Key Laboratory of Advanced Welding Production Technology,
Harbin Institute of Technology,Harbin 150001, China;
2. Key Lab of Liquid Structure and Heredity of Materials,
Shandong University, Jinan 250061, China)
Harbin Institute of Technology,Harbin 150001, China;
2. Key Lab of Liquid Structure and Heredity of Materials,
Shandong University, Jinan 250061, China)
Abstract: The sound joints of Fe3Al intermetallics and Q235 low carbon steel dissimilar materials were made by vacuum diffusion bonding process at 1050-1100℃,9.8MPa held for 1h. Microstructure and composition characteristics at the interface of Fe3Al/Q235 were studied by means of scanning electron microscopy(SEM), X-ray diffractometry(XRD), electron probe micro-analysis(EPMA) and transmission electron microscopy(TEM). The results indicate there exits FeAl phases and α-Fe (Al) solid solution near the Fe3Al/Q235 interface. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe3Al with DO3 type body-centered cubic (bcc) structure to α-Fe (Al) solid solution, and both structures have an orientation relationship of crystal (11-0)α-Fe(Al)‖(011)Fe3Al and ［001］α-Fe(Al)‖［100］Fe3Al. Based on this, a formation mechanism of the interface structure was elucidated.
Key words: Fe3Al intermetallics; vacuum diffusion bonding; microstructure; element transition