Microstructure and mechanical properties of a novel rapidly solidified, high-temperature Al-alloy

• Published in: Materials characterization 2016-02, Vol.112, p.142-148
• Main Authors: Overman, N.R., Mathaudhu, S.N., Choi, J.P., Roosendaal, T.J., Pitman, S.
• Format: Article
• Language: English
• Subjects: Alloy; Alloys; Aluminum; Aluminum alloy; Consolidation; Cooling rate; Flake; Flakes; Melt spinning; Microstructure; Phase Decomposition; Rapid Solidification; Shot
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2015.12.015

Rapid solidification (RS) processing, as a production method, offers a variety of unique properties based on far-from-equilibrium microstructures obtained through rapid cooling rates. In this study, we seek to investigate the microstructures and properties of a novel Al-alloy specifically designed for high temperature mechanical stability. Synthesis of, AlFe11.4Si1.8V1.6Mn0.9 (wt.%), was performed by two approaches: rotating cup atomization (“shot”) and melt spinning (“flake”). These methods were chosen because of their ability to produce alloys with tailored microstructures due to their inherent differences in cooling rate. The as-solidified precursor materials were microstructurally characterized with electron microscopy. The results show that the higher cooling rate flake material exhibited the formation of nanocrystalline regions as well additional phase morphologies not seen in the shot material. Secondary dendritic branching in the flake material was on the order of 0.1–0.25μm whereas branching in the shot material was 0.5–1.0μm. Consolidated and extruded material from both precursor materials was mechanically evaluated at both ambient and high (300°C) temperature. The consolidated RS flake material is shown to exhibit higher strengths than the shot material. The ultimate tensile strength of the melt spun flake was reported as 544.2MPa at room temperature and 298.0MPa at 300°C. These results forecast the ability to design alloys and processing approaches with unique non-equilibrium microstructures with robust mechanical properties at elevated temperatures. •A novel alloy, AlFe11.4Si1.8V1.6Mn0.9 was fabricated by rapid solidification.•Room temperature yield strength exceeded 500MPa.•Elevated temperature (300°C) yield strength exceeded 275MPa.•Forging, after extrusion of the alloy resulted in microstructural coarsening.•Decreased strength and ductility was identified as a result of forging.