Study On The Characteristics Of Bulk Amorphous Alloy Structure Evolution As Stress Induced

The amorphous alloy has the excellent mechanical properties such as high strength, highhardness. However, the plastic deformation ability of the bulk amorphous alloy at roomtemperature is especially bad, and it is restricted its application in the field of engineeringmaterials. The plastic deformation of bulk amorphous alloys at room temperature areimplemented through shear bands，and microstructure the stress induced has a crucial effecton shear bands space propagation. This article study the amorphous alloy microstructureevolution characteristics as the induced stress by the compression experiment ofmacroscopic mechanical properties testing and the nanoindentation experiments ofmicrocosmic mechanics performance testing.The article uses the bulk amorphous alloy Zr52.5Al10Cu17.9Ni14.6Ti5(Vit.105)as experimentobject. Through using X-ray diffraction (XRD), scanning electron microscope (SEM) anddifferential thermal analyzer (DSC), the article illustrate the characteristics of bulk amorphousalloy structure evolution as stress induced. The research results are as follows:To Vit.105rod specimen of bulk amorphous alloy with high to diameter ratio (h/r=0.6)taking cyclic loading in different loading rate, the result were found apparent anelasticphenomenon from the stress-strain curve, and anelasticity is increased with the increase ofloading rate decreases and the energy consumption ΔE value in the process of cyclic loadingis inversely proportional to the loading rate. The traditional crystalline metal alloy materials isinconsistent with amorphous alloy anelasticity. This illustrate that in the paper experimentalrange of loading rate, energy expenditure ΔE should be related to the time of stress effect. Theanalysis shows that not only shear bands internal region take place structure evolution but alsoexternal of shear bands will be made by elastic stress. Outside area of shear bandsmicrostructure is changing which will increase the free volume. The energy consumption ΔEvalues in the process of cyclic loading can be used as a parameter to characterizationamorphous alloy shear bands space proliferation; the higher energy consumption ΔE valuebulk indicate amorphous alloys have fine the shear bands space proliferation ability.Adopting Vit.105slab bulk amorphous alloy specimen in the nanoindentation experimentand using controling load model experiment method. From the experimental results, along with the increase of loading rate and keeping load, the creep phenomenon is the more obvious.The creep phenomenon of samples after the heat treatment is not obvious comparing withas-cast sample. The analysis results show that strain rate sensitivity m dynamic value reflectthe microstructure evolution of the amorphous alloy. The bigger the m value is correspondingto the amorphous alloy stronger shear band space proliferation ability, on the contrary thesmaller the m value is corresponding to the amorphous alloy weaker shear bands spaceproliferation ability.