Thermal Treatment, Sliding Wear and Saline Corrosion of Al In Situ Reinforced with Mg2Si and Ex Situ Reinforced with TiC Particles

• Published in: Journal of materials engineering and performance Vol. 27; no. 10; pp. 5030 - 5039
• Main Authors: Lekatou, A. G., Poulia, A., Mavros, H., Karantzalis, A. E.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2018
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Tribology; Si/TiC interface; ex situ TiC/Al; localized corrosion; in situ Mg; Si/Al; solidification; Mg; heat treatment; sliding wear
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-018-3213-1

The main objective of this work is to produce a composite consisting of (a) a cast heat-treatable Al-Mg-Si alloy with high contents of Mg for corrosion resistance and Si to offset the Mg-due poor castability (in situ hypoeutectic Mg 2 Si/Al composite) and (b) TiC particles at high enough volume fractions (≤ 15%), in order to achieve a satisfactory combination of wear and corrosion performance. TiCp/Al-7Mg-5Si (wt.%) composites were produced by flux-assisted casting followed by solution and aging heat treatment. Solution treatment led to a relatively uniform dispersion and shape rounding of Mg 2 Si precipitates and Si particles. TiC particle addition resulted in refinement of primary Al, modification of the Mg 2 Si Chinese script morphology and refinement/spheroidization of primary Mg 2 Si. Heat treatment combined with TiC addition notably improved the sliding wear resistance of Al-7Mg-5Si. A wear mechanism has been proposed. The TiC/Al interfaces remained intact of corrosion during potentiodynamic polarization of the heat-treated materials in 3.5 wt.% NaCl. Different main forms of localized corrosion in 3.5 wt.% NaCl were identified for each TiC content (0, 5, 15 vol.%), depending on specific degradation favoring microstructural features (topology/size/interface wetting) at each composition.