High-strength aluminum alloys containing nanoquasicrystalline particles

Abstract

By the use of homogeneous dispersion of nanoscale quasicrystalline particles in fcc-Al phase, new Al-based alloys with useful mechanical properties were developed. The structure consists of nanoscale icosahedral particles with a size of 30–50 nm surrounded by fcc-Al with a thickness of about 5–10 nm and no high-angle grain boundary is observed in the Al phase. The icosahedral phase has a high volume fraction of 60–70%. The unique structure is formed by the unique solidification mode in which the icosahedral phase precipitates as a primary phase followed by solidification of Al phase from the remaining liquid. The features of mechanical properties for the nanoquasicrystalline alloys are classified into three types, i.e. high tensile strength type of 800 MPa in Al–Cr–Ce–Co and Al–Mn–Ce–Co systems high elongation type of 30% in Al–Mn–Cu–Co system and high elevated temperature strength type of 500 MPa at 473 K and 350 MPa at 573 K in Al–Fe–Cr–Ti system. These mechanical properties are superior to those for the conventional Al-based crystalline alloys and the extension of the new Al-based alloys to practical application has also been described.