Effect Of Hollow Cone High-pressure Torsion On Thermal Stability And Mechanical Properties Of Zr_64.13Cu_15.75Ni_10.12Al₁₀ Bulk Metallic Glass

Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass were chosen to be the research object in the paper,hollow cone Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass was prepared for the first time and effect of hollow cone high-pressure torsion deformation on thermodynamics and mechanical properties of Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass was investigated.Copper mould with inner structure of hollow conical was designed and manufactured,then hollow cone Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass with bottom diameter of 19.8 mm,height of 14.0 mm and wall thickness of 1.2 mm was successfully prepared by arc melting melting suction casting method.The prepared bulk metallic glass was used in the experiment of hollow cone high-pressure torsion.Effect of hollow cone high-pressure torsion on thermodynamic properties of hollow cone Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass were investigated by X-ray diffraction?XRD?,differential scanning calorimetry?DSC?and thermal expansion test.The results showed that hollow cone bulk metallic glass was still amorphous structure after hollow cone high-pressure torsion process.In addition,temperatures of glass transition?Tg?and crystallization?Tx?,and supercooled liquid region increased,while thermal expansion coefficient decreased.Therefore,thermal stability of hollow cone high-pressure torsion processed bulk metallic glass has been improved,which was related to a large number of free volume generated in the high-pressure torsion processed bulk metallic glass.Mechanical properties of hollow cone high-pressure torsion processed Zr_64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass were investigated by experiments of hardness,elastic modulus and wear resistance.It is shown that hardness and elasticity modulus of hollow cone high-pressure torsion processed Zr-based bulk metallic glass were reduced due to the increase of free volume in the hollow cone high-pressure torsion processed specimen.In the friction and wear test of hollow cone high-pressure torsion processed bulk metallic glass,the friction coefficient increased and wear loss decreased,which indicated that the wear resistance increased under the same condition of sliding dry friction.The staggered shear bands occurred in the hollow cone high-pressure torsion processed specimen due to abrasive wear of bulk metallic glass,which inhibited the crack formation during the wear process.When the amount of crack reached the critical value,the material would peel off as flakes.Therefore,due to the reduction amount of cracks during hollow cone high-pressure torsion process,wear loss reduced and wear resistance improved.