Yuma Horio

Formation and mechanical properties of amorphous AlNiNd alloys

Al-based amorphous alloys with high tensile fracture strength of above 1000 MPa were found to form in the range 2-14 at.% Ni and 1-6 at.% Nd rapidly solidified Al-Ni-Nd alloys. Furthermore, the homogeneous dispersion of nanoscale f.c.c.-Al particles in the amorphous matrix causes a significant increase in of. The highest σ f values are 1040 MPa for Al 94 Ni 2 Nd 4 and 1050 MPa for Al 90 Ni 8 Nd 2 . Thus, in Nd-containing alloys, high or values above 1000 MPa are obtained for a higher Al concentration compared with other Al-based amorphous alloys containing Y, La or Ce as the lanthanide (Ln) element

New Al-based amorphous alloys with high mechanical strength in the AlNiM and AlCoM (M = Mn, Fe, Co, Ni) systems

Abstract It has been found that new amorphous alloys with high strength and good bending ductility are formed in the AlNiM1 (M1 = Mn, Fe, Co) and AlCoM2 (M2 = Mn, Fe) systems by the melt spinning technique. The comparison ranges in which the amorphous single phase and the coexistent amorphous and Al phases form extends from 87 to 94 at.% Al. The highest values of tensile fracture strength σf and Vickers hardness Hv for the amorphous single phase are 1070 MPa and 320 respectively for AlNiCo alloys. As the cooling rate decreases, the structure changes to mixed Al and amorphous phases, and σf and Hv increase to 1270 MPa and 360 respectively without detriment to ductility in the mixed state where the volume fraction of Al phase is about 20%. The highest σf value in the mixed state was 1340 MPa for the AlCoFe system. These high σf values are presumably due to the high strength of Al particles resulting from the absence of internal defects as well as of the effective barrier of the Al particles against shear deformation of the amorphous matrix.

High strength Al-based alloys consisting of fcc-Al and nanoscale icosahedral phases in Al-Mn-Co and Al-Mn-Ni systems

The homogeneous dispersion of nanoscale icosahedral (I) particles into an fcc-Al matrix by rapid solidification of Al-Mn-Co and Al-Mn-Ni alloys was found to bring about high tensile fracture strength (σ) without detriment to good bending ductility. The particle size of the I-phase and the width of the Al phase are about 25 to 100 nm and 5 to 15 nm, respectively. The highest σ values reaches as high as 1200 MPa for the Al 31 Mn 7 Ni 2 alloy. Thus, the addition of Co and Ni elements to Al-Mn alloys is effective for the achievement of high mechanical strengths and good ductility through the nanoscale structural modification resulting from the increase in quenching effect.