Stress Induced Microstructure Evaluation Of Temperature Dependence And It's Relationship To Plastic Deformation In Amorphous Alloys

Amorphous alloys'plastic deformation at room temperature is by way of highly localized shear band and the limited number of shear band leads to amorphous alloy presents a remarkable brittleness at room temperature,which restricts application in engineering field.The nucleation and extension of shear bands depend on microstructure,and structural evolution is closely related to loading environment.Based on the as-cast Vit.105 amorphous alloys,starting from the temperature dependence of microstructure evolution induced by stress,analyses the influence of pretreatment temperature Vit.105 amorphous alloy microstructure evolution and mechanical behavior:Vit.105 bulk amorphous alloys were lateral-pressured with quasi static at 150?room temperature(RT),100?and 150?,lateral pressure load of 9 kN.The results from DSC show that the samples pretreated at-150?temperature induced highest worth of relaxation enthalpy change(?H_r),which means it induced more free volume.Meanwhile Vickers hardness test show that hardness of pretreated samples is lower than the as-cast,we soften amorphous alloys and force brittle transform into plastic.Through uniaxial compression test,the engineering stress-strain curve reflects the change of mechanical behavior,samples pretreated at-150?manifest the best plastic deformation ability.Meanwhile the temperature rising of shear bands is the minimum,which is helpful to prevent the expansion of the shear band.We found more intensive vein organization and shear bands,and the mutual intersection between shear bands is more obvious in samples treated at-150?through analyzing appearance of fracture and profile.It is found that the plastic deformation of amorphous alloy is directly related to the thickness reduction through rolling at low temperature,The results from DSC show that the samples with 9%thickness reduction induced highest worth of relaxation enthalpy change(?H_r).The 5%and 7%reduction rolled at low temperature will bring the best plastic deformation.Through SEM observation,the crack was observed in the samples with 9%thickness reduction,which leaded young's modulus decreased,the strength and the plastic deformation also decreased.The increase of free volume in amorphous alloys will prompting nucleation of shear bands under stress,smaller temperature rising makes alloy's viscosity and temperature better recovery.Interaction of those factors enhance the ability of plastic deformation.