Study On Cu-based Amorphous Alloy Crystallization Behavior

By employing the differential scanning calorimetry calorimeter (DSC), X-ray diffraction and universal test enginery,the non-isothermal crystallization behavior of Cu_44.25Ag_14.75Zr₃₆Ti₅ amorphous alloy,Crystallization activation energy rate changes of different cooling,the effect of the compressive mechanical properties at room temperature on partially crystallized and fully crystallized. the following results can be obtained:With the increase of heating rate, the crystallization peaks shift to high temperature, crystallization kinetics is significant. Its non-isothermal crystallization mechanism is composed of the processes of three types,the first two steps of temperature boundary is not obvious especially in high heating rate. the first and second crystallization peak of the crystallization activation energy was calculated by Kissinger method and Ozawa method. the first crystallization peak of the crystallization activation energy is always more small than the second peak of crystallization activation energy.Under different cooling rate ,the amorphous alloy which was preparated with the same components have different crystallization activation energy. the more quickly the cooling rate is,the higher, the crystallization activation energy is, and the better thermal stability. When the crystallization volume fraction is about 65.5%, nucleation and nuclei growth happen in the previous stage and then begin to normal growth. Meanwhile the nuclei growth is controlled by three-dimensional diffusion. Above of this is the non-isothermal crystallization mechanism of amorphous alloy of Cu_44.25Ag_14.75Zr₃₆Ti₅.The compression mechanical properties tests of the different Crystallization heat treatment showed that the crystallization of amorphous alloy rod of Cu_44.25Ag_14.75Zr₃₆Ti₅ had significant influence on the mechanical properties. the Difference of the mechanical properties is great after the different crystallization heat treatment. In the 5 x 10^-2 strain rate the compressive strength of its amorphous alloy cast rods and completion of the first, second, three-step crystallization reaction were 1685 MPa,1331MPa,447MP and 247MPa. After the second step crystallization, the brittle phase Cu₁₀Zr₇ precipitated in amorphous alloy matrix ,which making the compressive strength rapid decline. After the third step crystallization, the brittle phase Cu₁₀Zr₇ is the main crystalline phase, and making the mechanical properties further deterioration.