Microstructural Evolution of Al-1Fe (Weight Percent) Alloy During Accumulative Continuous Extrusion Forming
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Microstructural Evolution of Al-1Fe (Weight Percent) Alloy During Accumulative Continuous Extrusion Forming XIANG WANG, REN-GUO GUAN, DI TIE, YING-QIU SHANG, HONG-MEI JIN, and HONG-CHAO LI As a new microstructure refining method, accumulative continuous extrusion forming (ACEF) cannot only refine metal matrix but also refine the phases that exist in it. In order to detect the refinements of grain and second phase during the process, Al-1Fe (wt pct) alloy was processed by ACEF, and the microstructural evolution was analyzed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Results revealed that the average grain size of Al-1Fe (wt pct) alloy decreased from 13 to 1.2 lm, and blocky Al3Fe phase with an average length of 300 nm was granulated to Al3Fe particle with an average diameter of 200 nm, after one pass of ACEF. Refinement of grain was attributed to continuous dynamic recrystallization (CDRX), and the granulation of Al3Fe phase included the spheroidization resulting from deformation heat and the fragmentation caused by the coupling effects of strain and thermal effect. The spheroidization worked in almost the entire deformation process, while the fragmentation required strain accumulation. However, fragmentation contributed more than spheroidization. Al3Fe particle stimulated the formation of substructure and retarded the migration of recrystallized grain boundary, but the effect of Al3Fe phase on refinement of grain could only be determined by the contrastive investigation of Al-1Fe (wt pct) alloy and pure Al. https://doi.org/10.1007/s11663-018-1185-z Ó The Minerals, Metals & Materials Society and ASM International 2018
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INTRODUCTION
DUE to the excellent properties of heat resistance, wear resistance, and corrosion resistance, Al-Fe alloys are gaining more and more attention from automotive and aircraft industries.[1–3] Addition of iron in Al alloys can improve the heat resistance of Al alloys due to the dispersed Al-Fe phases.[4] However, hard, brittle, and needlelike Al-Fe phases tend to cause stress concentration and dissever Al matrix, and the tensile strengths of Al-Fe alloys are still insufficient.[5,6] The maximum equilibrium solubility of Fe in Al alloys is 0.052 wt pct,[7,8] and Al-Fe phases are easy to form because Fe is one of the most common impurity elements in Al alloy and it cannot be completely removed from Al melt.[9,10] How to improve the comprehensive performance of Al
XIANG WANG and REN-GUO GUAN are with the School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China, and the School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China. Contact email: [email protected] DI TIE, YING-QIU SHANG, HONG-MEI JIN, and HONG-CHAO LI are with the School of Materials Science and Engineering, Northeastern University. Manuscript submitted July 27, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
alloys by overcoming the harmful effect of iron has become a hot research topic.[11] It is reported tha
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