Heat-Resistant Al Alloys: Microstructural Design and Preparation
SUN Jun(), LIU Gang, YANG Chong, ZHANG Peng, XUE Hang
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
Cite this article:
SUN Jun, LIU Gang, YANG Chong, ZHANG Peng, XUE Hang. Heat-Resistant Al Alloys: Microstructural Design and Preparation. Acta Metall Sin, 2025, 61(4): 521-525.
Aluminum (Al) alloys, a typical lightweight material, are limited to applications at temperatures below about 200 oC. The high-temperature range of 300-400 oC has been a longstanding bottleneck for traditional Al alloys. In this study, the underlying mechanisms of this service bottleneck are first discussed, and key scientific solutions aimed at overcoming the bottleneck are proposed. A new microstructure designing strategy is proposed to develop advanced heat-resistant Al alloys through phase transformation that couples rapidly diffusing solute atoms with slowly diffusing ones. This strategy leads to three design approaches for thermal stability: (1) interfacial solute segregation at the nanoprecipitate/matrix interfaces, (2) interstitial solute ordering within the coherent nanoprecipitates, and (3) multiple interfacial coherency coupling with multiscale microstructural features. By manipulating the microalloying effect at the atomic length scale, a series of 300-400 oC heat-resistant Al alloys were developed. Furthermore, the potential development directions of the heat-resistant Al alloys are also explored as possible references for future work.
Fund: National Natural Science Foundation of China(U23A6013, 92360301, U2330203);Programme of Introducing Talents of Discipline to Universities(BP2018008)
Corresponding Authors:
SUN Jun, academician of the Chinese Academy of Sciences, professor,Tel: (029)82667143, E-mail: junsun@mail.xjtu.edu.cn
Fig.1 Temperature-dependent diffusivity of typical solutes[6,7] (a) and 400 oC diffusivity vs excess solid solubility (Cmax - C400: the difference between the maximum solid solubility and the solid solubility at 400 oC, atomic fraction, %) of typical solutes[5] (b) in Al alloys
Fig.2 Representative high-angle annular dark field (HAADF) image and corresponding Cu and Sc mappings of a cross-sectioned θ'-Al2Cu nanoprecipitate in the Al-Cu-Sc alloy[10] (a) and dependence of steady state creep rate on creep stress at 300 oC, in comparison with available data of other Al alloys and Al-based composites (b) (Arrow in Fig.2b indicates an increase in creep property achieved in our work)
Fig.3 Representative HAADF image to show the crystal structure of V phase, viewed along [010] (Insets show the corresponding fast Fourier transform image (top right) and colorized Z-contrast image (middle right). In top right image, an additional set of patterns is clearly detected (marked by yellow arrows) that indicate a substructure. Green, red, and blue colors in the structural sketch (bottom right) represent Al, Cu, and Sc atoms, respectively) (a), representative HAADF image showing the Ω→V in situ phase transformation induced by the Sc intake at the coherent ledge (CL) (b), and tensile stress-strain curves at 400 oC, showing the tensile strength > 100 MPa achieved in Al-Cu-Mg-Ag-Sc alloy much greater than that in other comparing alloys (The inset figure demonstrates that the tensile strength > 100 MPa at 400 oC is over one time of all the reported Al alloys. HT—high temperature of 400 oC, RT—room temperature) (c)[5]
Fig.4 Representative SEM (a), TEM (b), and APT (c) images showing the multiscale microstructural features in the Al-Ce-Cu-Sc alloy; and dependence of steady state creep rate on creep stress at 300 oC, in comparison with its Sc-free Al alloys (d)
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