Preparation And Plastic Deformation Of Zr_62.4Cu_14.4Ni_9.6Al_9.6Fe₄ Bulk Metallic Glass

Metallic glasses?BMGs?are mainly composed of metal elements,with short-range order and long-rage disorder atomic arrangement structure of amorphous alloy.Because of the unique structural characteristics,BMGs exhibit excellent physical,chemical,biological and mechanical properties,such as high strength and hardness,high elastic and toughness and corrosion resistance.These excellent properties make BMGs become new potential functional materials with great application prospects.However,due to shear localization and work softening,the plastic deformation of BMGs at room temperature is highly localized into shear bands and usually the primary shear band propagates along with load 45° direction rapidly,resulting in catastrophic failure and restricting plastic strain.In addition,due to the sensitivity of the structure on their composition,minor element addition has been shown to be effective to improve the brittleness of the metallic glass.Therefore,exploring and broadening new multi-component BMGs system with glass forming ability?GFA?,high plasticity and strength by the mean of minor element addition is very meaningful.Furthermore,the qualitative and quantitative analysis of the distribution of shear bands also helps us understand the mechanism of non-uniform plastic deformation of BMGs.In addition,shear bands have lower density and more free volume compared to the substrate metal glass,which can be served as glass/glass interface and if the spacing of shear bands reach nanoscale,we will achieve a new type of material-nanoglass.This will give us a new method for the preparation of fully dense nano-glass,we can introduce a large amount of shear bands by non-uniform plastic deformation.Thus,we study the influence of aspect ratio and surface modification on the evolution of shear bands and look forward to prepare nano-glass.With the addition of minor Fe into the Zr₆₅Cu₁₅Ni₁₀Al₁₀ BMG,a new Zr_62.4Cu_14.4Ni_9.6Al_9.6Fe₄ glassy system with high glass forming ability and good mechanical properties was prepared by the copper mold casting method in our present work.The effects of Fe addition on GFA and mechanical properties of the Zr₆₅Cu₁₅Ni₁₀Al₁₀ alloy were investigated and discussed.The reduced glass transition temperature Trg of Zr_62.4Cu_14.4Ni_9.6Al_9.6Fe₄ BMG increases from 0.559 to 0.575,the ? parameter increases from 1.457 to 1.515,and the ? parameter increases from 0.642 to 0.644.The Zr_62.4Cu_14.4Ni_9.6Al_9.6Fe₄ bulk metallic glass exhibits a large plastic strain in compression of around 77.4%,a high yield strength of up to 1688 MPa,and a high hardness of 5.29 GPa in comparison with a plastic strain of 15.1%,a yield strength of 1572 MPa,and a hardness of 5.02 GPa of the Zr₆₅Cu₁₅Ni₁₀Al₁₀ BMG.And the evolution of shear bands in deformation process was also explored.We get a conclusion that the number of shear bands and the proportion of fine shear bands increase with strain.When the sample strain accesses 77.4%,the average spacing of shear bands is 1.015 ?m.In addition,the influence of aspect ratio on the shear band distribution shows that the shear band density of Zr_62.4Cu_14.4Ni_9.6Al_9.6Fe₄ BMG at the same strain increases with the aspect ratio.When the aspect ratio is 2.00,the average shear band spacing of the strain of 57% reaches a minimum of 2.019 ?m.The effect of surface modification on the shear band density is not significant.