準結晶を含むAl-6.3%Fe-3.8%Cr-3.3%Ti合金P/M材の組織と機械的性質 Structure and mechanical properties of Al-6.3 mass% Fe-3.8 mass% Cr-3.3 mass% Ti P/M alloys containing quasicrystals
AFCT–26P/M and AFCT–125P/M were prepared by extruding of Al–6.3 mass%Fe–3.8 mass%Cr–3.3 mass% Ti (AFCT) alloy powders at 673 K, of which the sizes were smaller than 26 μm and 125 μm, respectively. X-ray diffraction showed that the AFCT powder consists of three phases of icosahedral quasicrystal, fcc-Al and Al<sub>23</sub>Ti<sub>9</sub>. Both AFCT–P/M alloys have also the same structure as the powder. The ultimate tensile strength (<sub>UTS</sub>) , plastic elongation (ε<sub>P</sub>), Young's modules (<i>E</i>), Vickers hardness (HV), Density (ρ) and specific strength (σ<sub>UTS</sub>/ρ) at room temperature are 646 MPa, 4.4%, 86 GPa, 192, 2.951 Mg·m<sup>−3</sup> and 2.19 × 10<sup>5</sup> Nm·kg<sup>−1</sup> for AFCT–26P/M alloy and 541 MPa, 7.3%, 83 GPa, 165, 2.955 Mg·m<sup>−3</sup> and 1.83 ×10<sup>5</sup> Nm·kg<sup>−1</sup> for AFCT–125P/M alloy, respectively. After heating for 300 s at 573 K, σ<sub>UTS</sub>, σ<sub>0.2</sub> and ε<sub>P</sub> are 361 MPa, 333 MPa, 1.5% for AFCT–26P/M alloy and 286 MPa, 270 MPa, 6.5% for AFCT–125P/M alloy, respectively. It is confirmed by a transmission electron microscope (TEM) that icosahedral quasicrystalline particles with a size of about 400 nm precipitate in both P/M alloys. It was found that the AFCT–26P/M alloy having elevated-temperature strength contains icosahedral quasicrystalline particles even after heat-treatment for 720 ks at 573 K.
軽金属 48(6), 263-268, 1998-06-30
The Japan Institute of Light Metals