| Title |
Elevated - Temperature Strength of Amorphous Al - Ni - Fe - Nd Alloys |
| Authors |
김영환(Yeong Hwan Kim) ; 황계홍(Kye Hong Hwang) ; 윤기혁(Ki Hyuk Yun) |
| Abstract |
Amorphous Al_(88)Ni_(10-x)Fe_xNd₂(x=0,3,5 at%) alloys with the two-stage crystallization process of amorphous→amorphous plus Al→Al plus compounds were found to exhibit high ultimate tensile strengths(σ_B) above 800MPa in the temperature range of room temperature to 580K and a large fracture elongations(ε_f) above about 20% at the exothermic peak temperature of Al phase(T_(P1)) in the DSC curve. The maximum value of σ_B and ε_f in the temperature range from the precipitation onset temperature of Al phase to 580K shifts toward the higher temperature side with the replacement of Ni by Fe element. This compositional dependence is thought because a number of the defect-free Al particles with a high heat-resistance against mechanical strenghth and growth of the particles at elevated temperatures precipitate at a higher temperature range with increasing Fe content. The appearance of the large elongation at T_(P1) can be explained by a crystallization-induced plasticity phenomenon which occur through the continuous propagation of the deformation site resulting from the hardening effect of the defect-free Al particles which preferentially precipitated on the shear plane by the local adiabatic heating in the stress-concentrated area. |