Significantly enhanced fatigue resistance and mechanisms of hypoeutectic Al-Si composite calibrated using trace in-situ nanocrystals

Document Type

Journal Article

Publication Title

Composites Part B: Engineering

Volume

271

Publisher

Elsevier

School

School of Engineering

RAS ID

64703

Funders

National Natural Science Foundation of China / Science and Technology Development Program of Jilin Province, China / Exploration Foundation of State Key Laboratory of Automotive Simulation and Control / Undergraduate Innovation Fund of Jilin University, China

Comments

Liu, T. S., Zhu, L., Yang, H. Y., Cui, H. Y., Meng, J., Qiu, F., . . . Zhang, L. C. (2024). Significantly enhanced fatigue resistance and mechanisms of hypoeutectic Al-Si composite calibrated using trace in-situ nanocrystals. Composites Part B: Engineering, 271, article 111138. https://doi.org/10.1016/j.compositesb.2023.111138

Abstract

Fatigue resistance under extreme stress conditions is an important indicator to evaluate industrial application potential of Al-Si-Mg alloys, but their fatigue resistance is inherently weakened by large grain size, long-needle Si phases and coarse precipitates. This work reports significantly optimized microstructure configuration and fatigue resistance of hypoeutectic Al-Si composite optimized by the nanocrystallization products of a NiNbTi metallic glass. It was proved the in-situ NiTi (B2) nanocrystals can serve as the heterogeneous nucleation sites of -Al and -Mg2Si and the growth retarder of eutectic Si. Particularly, the optimized composite exhibited nearly 5 times and 6 times longer fatigue life than the unoptimized alloy at 120 MPa (60 Hz) and 240 MPa (20 Hz), respectively. The fatigue strength (N = 107) was increased by 21.7 % and 25.9 % at 60 Hz and 20 Hz, respectively. The -Al refinement enhanced the resistance to fatigue crack initiation. The refinement and spheroidization of eutectic Si phases reduced stress concentration. Also, the austenite-martensite phase transformation of NiTi afforded more energy for precipitation. Refined -Mg2Si and '' phases were facilitated to interact with dislocations, improving the resistance to dislocation slip during cyclic strain through the dislocation shearing effect. This work provides a theoretical basis for the future development of Al-Si alloys and composites with excellent fatigue resistance for expanding their industrial application scope.

DOI

10.1016/j.compositesb.2023.111138

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