Formation, Thermal Stability and Mechanical Properties of Aluminum-Based Glassy Alloys Containing Boron

抄録

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 + Al₃Ni + Al₄Ce for the Al-Ni-Ce-6%B alloy and through three stages of glass → Al + glass → Al + metastable phase + glass → Al + Al₉Co₂ + Al₃Y + Al₄NiY + 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.