Effects Of Additional Elements On The Glass Forming Ability And Properties Of Zr-based Amorphous Alloys

Element addition technique plays an effective and important role in incerasing the glass formation ability and improving mechanical properties and corrosion resistance of alloys.Moreover,it is an effective method to explore new amorphous materials and improve their properties.The effect of element addition on the properties of Zr-based amorphous were investigated by means of XRD,DSC,SEM,TEM,OM and electrochemical workstation in this thesis.The effect of Ag addition on the properties of Zr₆₅Al_7.5Ni₁₀Cu_17.5-xAg_x?x=0-17.5at%?glassy alloys were investigated.The glass transition phenomenon for 65Zr glassy alloys was observed in the Ag content range below about 15%and the icosahedral phase precipitated as the heating-induced primary phase in the limited Ag content range.In the higher Ag content range where glass transition is not clearly observed,the primary precipitation phase changed to mixed phases of tetragonal Zr₃Ag+tetragonal Zr₂Ni+hexagonal Zr₄Al₃.Although neither glass transition nor supercooled liquid region is observed for Zr₆₅Al_7.5Ni₁₀Ag_17.57.5 and no icosahedral phase is formed,a modified Zr₆₅Al_7.5Ni_17.5Ag₁₀0 alloy with higher Ni/Ag content ratio exhibits glass transition and supercooled liquid region and the primary precipitates also changes to an icosahedral phase.Besides,the 6%Ag-containing alloy keeps high glass-forming ability which is high enough to form a bulk glassy alloy rod of 6 mm by suction casting.The good correspondence between the appearance of glass transition and the icosahedral phase precipitation was recognized in the multicomponent glassy alloys.Then the effect of Ni addition on the properties of Zr₄₈Cu₃₆Al₈Ag_8-x-x Ni_x?x=0-8%?glass alloy were also investigated.It is demonstrated that the glass-forming ability decrease while the alloy still showed obvious supercooled region.The plasticity and strength became better with the addition of Ni.Besides,the corrosion resistance was enhanced in NaCl,H₂SO₄ and HCl.The decrease of Ag content makes the amorphous alloy system maintaining good GFA,corrosion resistance and high strength,reducing production cost,then can be used in mass production.