Speaker
Description
The demands from industry and daily live have required the development of structural materials. For example, the heat-resistant Al alloys are expected for the improved performance at higher temperatures (≥300℃) due to their lower density and reasonable cost. However, the traditional heat-resistant Al alloys (i.e., Al-Si, Al-Cu) can only sustain at 250℃ currently, because the rapid diffusion of main reinforcement elements (Si, Cu) should cause the microstructure coarsening and related performance degrade. Therefore, the slowly diffused elements (i.e., Fe, Ni, etc.) are introduced to Al matrix to form eutectic Al alloys, which is considered to have higher potential for high temperature applications.
Typically, the Al-Fe-Ni eutectic alloy was characterized as Al matrix and Al9FeNi compound, and the Al matrix was strengthened by Al9FeNi eutectic frame by load transfer effect. Afterwards, the thermal exposure experiments exhibited that the alloy can maintain long-time stable at 400℃. Beside the load transfer provided by eutectic structure, the Al matrix was designed to be strengthened by thermally stable precipitates synergistically. Herein, the well-known thermal-stable precipitates (Al3Sc or Al3(Sc, Zr)) were introduced to eutectic matrix by the mirco-alloying strategy. Eventually, the alloy hardness was improved significantly by Al3Sc. Furthermore, the co-additions of Sc with Zr improved the alloy performance at 400℃, and the hardness can keep stable at 400℃.
Creep is the critical aspect to evaluate the high temperature mechanical performance of eutectic alloys. Experiments demonstrate that both threshold stress and load transfer effect can be induced by Al9FeNi to improve creep resistance. Furthermore, the Sc addition can improve both threshold stress and load transfer effect of the eutectic alloy, but the influence of Sc is varied with the temperature. Both analytical modeling and Finite Element Analysis methods are used to explain the underlying mechanisms.
| Speaker Country | China |
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