| In recent years,Zr-based amorphous alloys have been widely studied due to their excellent amorphous forming ability and wide supercooled liquid phase region,with their excellent mechanical properties such as high strength and high hardness.However,the Zr-based amorphous alloy undergoes inhomogeneous deformation at room temperature,and catastrophic fracture occurs along a single shear zone,which limits the use of amorphous alloys as structural materials.When the deformation temperature is close to Tg(glass transition temperature),the amorphous alloy begins to undergo structural transformation and gradually produces uniform plastic deformation and viscous flow.The viscosity of the amorphous alloy becomes very sensitive to the change of temperature and strain rate,and the strength and plasticity of the amorphous alloy show great differences.It is found that the deformation behavior of Zr50Cu40Al10 amorphous alloy ribbons is affected by temperature and strain rate,but the high temperature deformation mechanism of bulk amorphous alloy is still not very clearly.Therefore,the bulk Zr50Cu40Al10 amorphous alloy was selected as the object of study,and the bulk Zr50Cu40Al10 amorphous alloy sample was prepared by copper mold casting.The high temperature deformation behavior of Zr50Cu40Al10 samples under different temperatures and strain rates was studied by tensile test.The fracture morphology of Zr50Cu40Al10 sample after tensile fracture was observed to study its micro-fracture behavior.The high temperature tensile test of the bulk Zr50Cu40Al10 amorphous alloy shows that the strain strengthening phenomenon is weak at the end of the high temperature tensile stress-strain curve when the strain rate is 3.33×10-4s-1 and the temperature is 430? and 440?.The lower the strain rate,the more obvious the phenomenon is.The enthalpy values of different parts of the bulk amorphous alloy were measured by DSC,and the difference of the crystal volume fraction between the deformed zone and the non-deformed zone was calculated by 8%,which showed that the deformation was conducive to the occurrence of crystallization.At room temperature,the fracture surface is vein-like,while at high temperature,a lot of plastic deformation occurs on the fracture surface without vein-like veins,showing better plasticity.At 440 ?,the strain rate of bulk Zr50Cu40Al10 amorphous alloy is in the range of 3.33×10-4s-1?1×10-2s-1.With the increase of strain rate,more free volume is produced in the amorphous alloy,and the aggregation of free volume leads to the softening of the amorphous alloy.The yield strength and tensile strength of bulk Zr50Cu40Al10 amorphous alloy decrease with the increase of strain rate. |
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