The Research On Superplastic And Crystallization Kinetics Of CoCrMoCBEr Amorphous Alloy

By employing the Compression at the high temperature test the transformation behaviors of the amorphous Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ alloy under different temperature and strain rate,confirm the effect of temperature and strain rate on the superplastic for this alloy and obtain the best parameter.By employing the X-ray diffraction and differential scanning calorimetry(DSC),the kinetics of glass transition and crystallization of Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ amorphous alloy at before deformation and affter deformation have been systematically investigated.The temperature and strain rate has an important influence on the rheology of the metallic Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ glass,rheology increased with the temperature gone up and rheology increased also with the strain rate reduce.At the temperature as 889K strain rate as l×10^-3the metallic Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ glass has a lower rheology stress as 99Mp,this condition very adapt to plastic machining.DSC curves of amorphous form before deformation and affter deformation Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ amorphous alloy only have one exothermal peak,and it can be confirmed that crystallization happened in one-step.Throuth contrast the acreage of exothermal peak about before deformation and affter deformation Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ amorphous alloy found that the acreage of before deformation always biger than the affter deformation at the rate of heat vary from 10K/min to 40K/min,further more the offspring of before deformation and affter deformation Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ has some different and the affter deformation have some offspring more than the before deformation.From above result we can get the conclusion about that the deformation has an influence of the crystallization reaction.The deformation has an important influence on the activation energy for crystallization of the metallic Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ glass.The non-isothermal crystallization of before deformation and affter deformation Co₄₈Cr₁₅Mo₁₄C₁₅B₆Er₂ amorphous alloy is though the way nucleation ratio directness by Surinach fitting,the non-isothermal crystallization mechanism is composed of the processes of two types, namely the Johnson-Mehl-Avrami(JMA) nucleation-and-growth mode and the mode which has been well described by the normal grain growth kinetic law(NGG).At the beginning of crystallization the crystallization mechanism follow the JMA model,with the crystallized volume fraction increase the crystallization mechanism change to NGG model.