Microstructure and mechanical properties of ternary intermetallic compound dispersed P/M Al-Mn-X-Zr (x=Cu,Ni) alloys |
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Authors: | Hiroki Adachi Wataru Itaka Tetsuo Aida K Osamura Manabu Imaoka Jun Kusui |
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Affiliation: | (1) Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan;(2) Graduate School of Science and Engineering for Education, University of Toyama, Toyama 930-8555, Japan;(3) Research Institute for Applied Sciences, Kyoto 606-8202, Japan;(4) Powder & Paste Division, Toyo Aluminum K. K., Osaka 529-1608, Japan |
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Abstract: | Heat-resistant aluminum alloys are generally developed by dispersing stable intermetallic compounds by adding transition metals
(TM) whose diffusion coefficient in aluminum alloys is low even at high temperatures. Commonly used intermetallic compounds
include Al-TM binary intermetallic compounds, for example, Al6Fe, Al3Ti and Al3Ni. By contrast, multicomponent intermetallic compounds are hardly used. The present study focuses on Al-Mn-Cu and Al-Mn-Ni
ternary intermetallic compounds, and by finely dispersing these intermetallic compounds, attempts to develop heat-resistant
alloys. Through the atomization method, Al-(4.96–5.96)Mn-(6.82–7.53)Cu-0.4Zr and Al-(5.48–8.76)Mn-(2.23–4.32)Ni-0.4Zr (in
mass%) powders were fabricated, and by degassing these powders at 773 K, intermetallic compounds were precipitated. These
powders were then solidified into extrudates by hot extrusion at 773 K. The microstructural characterization of powders and
exrudates was carried out by XRD analysis, SEM/EDX and TEM. The mechanical properties of extrudates were determined at room
temperature, 523 K and 573 K. In Al-Mn-Cu alloys, while a small amount of Al2Cu was crystallized, precipitated Al20Mn3Cu2 intermetallic compounds were mainly dispersed. In Al-Mn-Ni alloys, while a small amount of Al6Mn intermetallic compounds was precipitated, the precipitated A60Mn11Ni4 intermetallic compounds were mainly dispersed. Both ternary intermetallic compounds were about 200 nm in size. The compounds
were elliptical, and their longitudinal direction was oriented along the extrusion direction. In the Al-Mn-Cu alloys, since
the work hardening at room temperature was high, the tensile strength became 569 MPa. At elevated temperatures, since hardly
any work hardening was observed, the tensile strength decreased markedly. However, in Al-Mn-Ni alloys, since the work hardening
is low even at room temperature, the roomtemperature strength is not high. Thus, the decrease in tensile strength at elevated
temperatures is relatively small and a high strength was obtained at 523 K and 573 K: 276 MPa and 207 MPa, respectively. |
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Keywords: | aluminium alloy heat resistant dispersion strengthening Al-Mn-Zr |
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