Investigation on the Microstructure of ECAP-Processed Iron-Aluminium Alloys

• Published in: Materials Vol. 14; no. 1; p. 219
• Main Authors: Behrens, Bernd-Arno, Brunotte, Kai, Petersen, Tom, Relge, Roman
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 05-01-2021; MDPI
• Subjects: bulk forming; Chemical composition; Ductility; Equal channel angular pressing; equal channel angular pressing (ECAP); Ferrous alloys; Grain boundaries; Grain growth; Grain refinement; Grain size; Heat treatment; Hot forming; Intermetallic compounds; Investigations; Iron; iron-aluminium alloys; Mechanical properties; Microstructure; Parameters; Powder metallurgy; Sulfur; Titanium alloys; Workpieces; bulk forming; equal channel angular pressing (ECAP); microstructure; iron-aluminium alloys; hot forming
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14010219

The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 °C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%-Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement.