High-strength Al-based alloys consisting mainly of nanoscale quasicrystalline or amorphous particles

This review deals with the microstructure and mechanical properties of Al-based nano-quasicrystalline(Q) and nano-amorphous (A) alloys obtained by rapid solidification. The nano-Q alloys are composed of icosahedral (I) particles with a size of 30 nm surrounded by an Al layer with a thickness of 10 nm for the Al-Cr-Ce and Al-Mn-Ce base alloys and the volume fraction of the I-phase is about 70%. The nano-Q alloys exhibit high tensile strength (sigma(1)) of 1350 MPa for the Al94.5Cr3Ce1Co1.5 alloy and the I particles have a short-range disorder and long-range I structure. The bulk I-based alloys produced by extrusion of I-based powders have sigma(f) of 500 to 850 MPa and elongations of 6 to 25%. The nano-A alloys consist of granular amorphous and Al phases with sizes of about 10 and I nm, respectively, for the Al-V-Fe alloys. The formation of the nanogranular A-phase is presumably due to the suppression of the transition from supercooled liquid to I-phase. The sigma(f) reaches 1390 MPa for the Al94V4Fe2 alloy and decreases by the transition to I+Al phases. These properties are excellent enough to demonstrate the validness of the structure control to nano-8 and nano-A phases.