Microstructures from Ni-Cr-Al diffusion couples illustrating “Three types of boundaries”
1997; Elsevier BV; Volume: 37; Issue: 5 Linguagem: Inglês
10.1016/s1359-6462(97)00145-0
ISSN1872-8456
Autores Tópico(s)Intermetallics and Advanced Alloy Properties
ResumoThe first-ever experimental results concerning the interdiffusion in the two-phase, γ+β region of the ternary system are presented, together with the theoretical interpretation of the observed phenomena. In the experimental part of the study, a number of two-phase diffusion couples made from cast Ni-Cr-Al alloys was studied at 1200 °C. The application of the novel wide-line Energy-dispersive X-ray Spectroscopy (WL-EDS) allowed for previously impossible quantitative measurements of the concentration profiles within the two-phase zones. The measured profiles, together with the determined diffusion paths, were compared to the results of the simulations performed with the use of two different models: the Engstrӧm et al. model (DICTRA) and multi-component multi-phase model. The results allowed verifying the existence of a number of previously postulated features typical for the multi-phase diffusion. The comparison of the experimental and simulated results confirms that the currently used theoretical models of the interdiffusion process enable a satisfactory description of the real process. Still, some of the observed features cannot be interpreted in the light of available theory, although some of them are likely caused by the non-uniform cast microstructures. The better agreement with the experimental data obtained with the use of multi-multi model suggests that the interdiffusion should be considered simultaneously in all phases present in the system.
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