Crystallization behavior, Al-Ce intermetallic formation, and microstructure refinement of near-eutectic Al–Si alloys by rare-earth element additions
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Bo Chi
Abstract
Near-eutectic Al-Si alloys have low strength and high brittleness because of the presence of many eutectic b-Si flakes, needle-like Al-Fe-Si intermetallics, and coarse α-Al grains. This study disclosed the effects of cerium-rich RE (rare earth) element modification on orientation characters of crystals, formation of Al-Ce compounds, and microstructural refinement to improve the microstructure and mechanical properties of the alloys. The RE addition depressed preferential growth along the close-packed and/or sub-closepacked planes and promoted growth along the non-closepacked planes, in which La and other elements were dissolved into needle-like Al11Ce3 phase. When the temperature decreased, Al11Ce3 was preferentially crystallized from the melts and then devitrified by attaching to the surface of β-Al5FeSi needles. Moreover, many small Al11Ce3 particles were precipitated in the matrix and on the Si surface by a T6 heat treatment. Eutectic β-Si phases were constructed into discontinuous networks, short rods, and even particles by RE additions, which were further transformed into fine nodules following the T6 treatment. α-Al grains and primary β-Al5FeSi needles were simultaneously refined. The addition of 1.0 wt.% REs and subsequent T6 treatment yielded the highest tensile strength, elongation, and hardness of the alloy.
© 2020 by Walter de Gruyter Berlin/Boston
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- Notifications
- DGM
- Conferences
- Imprint
Articles in the same Issue
- CONTENTS
- Original Contributions
- Residual stress analysis, mechanical and metallurgical properties of dissimilar weldments of Monel 400 and AISI 316
- Dry sliding wear behaviour of sub-zero processed Cr–V ledeburitic steel Vanadis 6 against three counterpart types
- Computational thermodynamics/kinetics aided design for the microstructure of pearlitic steels during cooling process
- Brazed coatings for steam turbine blades: impact of the tape architecture and composition on mechanical properties
- Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050
- Investigation of the effect of solidification rate on microstructure of Al-0.13Si-0.3Fe DC-cast alloy using EBSD and DSC techniques
- Crystallization behavior, Al-Ce intermetallic formation, and microstructure refinement of near-eutectic Al–Si alloys by rare-earth element additions
- Fuzzy multicriteria decision-making-based optimal Zn–Al alloy selection in corrosive environment
- Notifications
- DGM
- Conferences
- Imprint
