Formation, thermal stability and mechanical properties of aluminum-based glassy alloys containing boron

Glassy type Al-based alloys, with a distinct glass transition and a supercooled liquid region before crystallization, were formed in (Al _0.84Ni _0.1Ce _0.06) _100-xB _x(x = 0 to 10 at%) and (Al _0.84Ni _0.05Y _0.09Co _0.02) _100-xB _x(x = 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 (σ _f) and the highest values of H _v and σ _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 (ΔT _x = T _x -T _g),H _v and σ _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 ₃Ni + Al ₄Ce for the Al-Ni-Ce-6%B alloy and through three stages of glass → Al + glass → Al + metastable phase + glass → Al + Al ₉Co ₂ + Al ₃Y + Al ₄NiY + Al-Y-Ni-Co quaternary compound for the Al-Ni-Y-Co-2%B alloy. The finding of Al-based glassy alloys with large ΔT _x values above 30 K is encouraging for future development of Al-based alloys as a high strength material with light weight.