Zr_41.2Ti_13.8Cu_12.5Ni_10.0Be_22.5Amorphous Alloy Is Too Cold Study On The Mechanical Properties Of The Liquid Phase Region

As a new material,amorphous alloy has a unique atomic structure.Because of the short-range order and long range disorder of the atomic arrangement,there are no defects such as the dislocation grain boundary of the traditional metallic materials,so that it has the outstanding characteristics different from the traditional crystal metal materials,such as high hardness,high strength,excellent abrasion resistance,outstanding corrosion resistance and so on.Because of the special atomic structure of amorphous alloys,it has good plasticity and thermal processing properties in supercooled liquid region.In this paper,the thermal physical properties,the mechanical properties and plastic deformation mechanism of Zr_41.2Ti_13.8Cu_12.5Ni_10.0Be_22.5?Vit1?in supercooled liquid region are mainly investigated.The effects of temperature and strain rate on plastic deformation are studied.The effects of sedcond phase particles on crystal formation and shear band expansion were studied.The experimental material is provided by Liquidmetal?technologies,Inc.The structure and composition of purchased samples were detected by X-ray diffraction?XRD?,differential scanning calorimetry?DSC?,Scanning electron microscopy?SEM?and Energy Dispersive X-Ray Spectroscopy?EDX?.The thermal physical properties such as thermal conductivity,thermal expansion coefficient and high temperature resistivity of the sample were tested.Tensile and compressive experiments were carried out using the Gleeble 3500 thermal simulation test machine in the supercooled liquid region of Vit1?630.3K⁷20.1K?with the strain rate of 0.005²/s.The fracture surface and deformation zone were observed by SEM.The main studies were obtained as follows:XRD and SEM were used to determine the composition of the sample as Zr_41.2Ti_13.8Cu_12.5Ni_10.0Be_22.5 matrix and a small amount of ZrO particles?volume fraction less than 5%?.The DSC test determined that the glass transition temperature of the sample was T_g=630.3K,the crystallization starting temperature was T_x=720.1K,and the supercooled liquid region width?T_x=89.8K.The crystallization activation energy of the alloy was calculated by testing the characteristic temperature at different heating rates.The variation trend of thermal expansion coefficient,thermal conductivity and resistivity is basically in accordance with the crystallization process.The effects of temperature and strain rate on the deformation process of Vit1amorphous alloy were studied by Gleeble thermal simulation tester.It was found that the temperature and strain rate had different effects on the yield strength,yield drop and steady stress of the material.Yield strength,yield descent and steady-state stress decreased with increasing temperature.Yield strength,yield descent and steady-state stress increased with the increase of strain rate.By SEM,the influence of impurity particles on the shear zone movement was found that the shear band could be blocked by particles or bypassed in the process of expansion,and the influence of a small amount of impurities on the deformation process was negligible.After the analysis of the deformed samples by XRD,some crystals of the samples were found.Compared to other research on pure Vit1 alloy,the results showed that impurities promoted the crystallization of amorphous alloys,which was the same as the result of the comparison of crystallization activation.Crystallization would cause the increase of the viscosity of the alloy which had a certain effect on the mechanical properties.By Johnson-cook formula fitting the dynamic mechanical process of Vit1 amorphous alloy at high temperature,it is found that the Johnson-cook formula could be used to describe the flow stress change trend of Vit1 amorphous in high temperature deformation process.