Study On Preparing And Crystallzation Kinietics Of Cobalt-Based Amorphous Alloys

This text with the Co₄₃ Fe₂₀ Ta_5.5 B_31.5 and (Co₄₃ Fe₂₀ Ta_5.5 B_31.5)_100-xY_x alloys for research objects. The non-isothermal crystallization kinetics and it is crystal of the metallic Co₄₃Fe₂₀Ta_5.5B_31.5 glass has been studied. With the Co₄₃ Fe₂₀ Ta_5.5 B_31.5 metal alloy for foundation, add element Y, make use of rapid cooling on a single cooper wheel and vacuum copper mold casting method to make (Co₄₃ Fe₂₀ Ta_5.5 B_31.5)_100-xY_x amorphous alloy and amorphous rods.The DSC experiment expresses that the DSC curve of the amorphous alloy Co₄₃ Fe₂₀ Ta_5.5 B_31.5 appears two exothermic peaks. In the T_g neighborhood, 929 K temperature, the isothermal crystallization of the Co₄₃ Fe₂₀ Ta_5.5 B_31.5 amorphous alloy have studied.Experiment expresses:When the heat preservation 10 min, from the amorphous alloy body separate out small crystal grain.The crystal grain is along with the extension and aggrandizement in heat preservation time.When the heat preservation 55 min, the crystal grain grows up glomeration and the diameter of the globosity crystal grain is about 5 μm. When the heat preservation 10 min, the Br, Mr and Hc almost is zero.Along with the extension backed heat preservation for time, the coercivity Hc sharply enlarges. From the non-isothermal DSC thermogram for amorphous Co₄₃ Fe₂₀ Ta_5.5 B_31.5 ribbons, while anneal temperature as 1153 K, the Hc is 416 Oe, but while anneal temperature as 1273 K, the Hc again sharply lower, only have 152 Oe.The second exothermic peak at continuous heat under the condition, with heat speed of speed, the characteristic temperature T_p of alloys moves toward the high temperature area . The value of activation energy of the amorphous alloy depends strongly on both the adopted heating rate regime and adopted equation. For the volume fraction crystallized, x, E_c(x) dependence was obtained by Flynn-Wall-Ozawa method. Using the Surinach curve fitting procedure, the kinetics was specified that the crystallization are made by Johnson-Mehl-Avrami mode.For (Co₄₃ Fe₂₀ Ta_5.5 B_31.5)_100-xY_x(x=0.5,1,1.5,2,2.5,3) alloy research, express as a result:This series metal alloys all the amorphous alloy. The hot analysis discovers that add of just the right amount of element Y make T_x togo up, the T_g slightly has already go up, T_l show lower. Among them,( Co₄₃ Fe₂₀ Ta_5.5 B_31.5) 97 Y₃ alloy's T_rg =0.59, ΔT_x=93K, γ =0.422,can make the diameter 2mm amorphous rod, the GFA of metal alloy is the most strong . The fracture strength for the diameter 2mm of (Co₄₃ Fe₂₀ Ta_5.5 B_31.5)₉₇ Y₃ alloy is 1852 MPa. The compressive fracture angle are about 0° .The coercivity of (Co₄₃ Fe₂₀ Ta_5.5 B_31.5)₉₇ Y₃ is 327 Oe.