Solid State Amorphization Reaction by Rod-Milling Al_xTa_<1-x> Powders and the Effect of Annealing
High thermal stable amorphous Al_xTa_<1-x> alloy powders with wide amorphization range (10≤x≤90) have been synthesized by rod-milling technique using a mechanical alloying (MA) method. During the first few kiloseconds (11-173 ks) of the MA time, the layered-composite particles of Al and Ta are intermixed and form an amorphous phase upon heating at about 680 K in a differential thermal analyzer by thermally assisted solid state amorphization (TASSA). The heat formation of an amorphous Al_xTa_<1-x> alloy via the TASSA process, ΔH_<aT> has been measured as a function of the MA time. The crystallization characteristics indexed by the crystallization temperature, T_<xT> and the enthalpy of crystallization, ΔH_<xT> of the amorphous phase formed via the TASSA process are also investigated as a function of the MA time. Comparable with the TASSA process, a homogeneous amorphous Al_xTa_<1-x> alloy is formed after longer MA time (1080 ks). The amorphization process in this case is attributed to a mechanical solid state amorphization (MDSSA). At the end of the MA time (1080-1440 ks), the maximum heat of formation of an amorphous Al_xTa_<1-x> alloy via the MDSSA process, ΔH_<aM>, has been calculated. Moreover, the thermal stability characterized by the crystallization temperature, T_<xM> and the enthalpy of crystallization, ΔH_<xM>, are also estimated. The role of amorphization via each process has been discussed.
- Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy 43 (2), 135-143, 1997-03-25