Amorphous metallic alloys possess high strength characteristics, which are superior to crystalline materials. Here we report an influence of Sc addition on glass-forming ability, glass-transition behavior, supercooled liquid region, and mechanical properties of an Al84Y9Ni5Co2 glassy alloy. This paper also aims to present a promising (Al0.84Y0.09Ni0.05Co0.02)95Sc5 amorphous alloy. This alloy has an ultrahigh tensile fracture strength exceeding 1500 MPa, which surpasses those for all the other Al-based fully crystalline and amorphous alloys reported to date, in addition to high Young’s modulus of 78 GPa. The fracture surface of this new alloy exhibited vein pattern typical for amorphous alloys with good ductility, and multiple shear bandswere observed on the lateral surface. The ultrahigh tensile strength of the (Al0.84Y0.09Ni0.05Co0.02)95Sc5 amorphous alloy results from an increase in the interatomic constraint force by the addition of Sc, an element having highly negative enthalpy of mixing with Al, Ni, and Co and the highest chemical affinity with Al among the alloying elements.

The “fragile”–“strong glass” transition in Al-based alloys is observed as a function of Sc content. The Sc-bearing alloys suffer glass transition as well as Sc-free Al0.84Y0.09Ni0.05Co0.02 alloy, however, the value of ΔCp decreases drastically and comes within the variation of the baseline at higher than 2 at. % of Sc. The studied glasses are free from pre-existing nuclei.

Glassy type Al-based alloys, with a distinct glass transition and a supercooled liquid region before crystallization, were formed in (Al 0:84 Ni 0:1 Ce 0:06 ) 100Àx B x (x ¼ 0 to 10 at%) and (Al 0:84 Ni 0:05 Y 0:09 Co 0:02 ) 100Àx B x (x ¼ 0 to 3 at%) systems by melt spinning. The addition of an optimum amount of B was found to increase the temperature interval of supercooled liquid region from 18 K to 23 K at 6%B for the former system and from 28 K to 31 K at 1.5 and 2%B for the latter system. The similar increase with B content was also recognized for Vickers hardness (H v ) and tensile fracture strength ( f ) and the highest values of H v and f are 400 and 1060 MPa, respectively, at 6%B and 375 and 1140 MPa, respectively, at 1.5%B. The maximum phenomena of temperature interval of supercooled liquid region (ÁT x ¼ T x À T g ), H v and f at optimum B contents can be interpreted in the framework of the three empirical component rules for the stabilization of supercooled liquid and the formation of bulk glassy alloys. The crystallization occurs through two stages of glass ! Al + metastable phase ! Al + Al 3 Ni + Al 4 Ce for the Al-Ni-Ce-6%B alloy and through three stages of glass ! Al + glass ! Al + metastable phase + glass ! Al + Al 9 Co 2 + Al 3 Y + Al 4 NiY + Al-Y-Ni-Co quaternary compound for the Al-Ni-Y-Co-2%B alloy. The finding of Al-based glassy alloys with large ÁT x values above 30 K is encouraging for future development of Al-based alloys as a high strength material with light weight.