Study On Preparation And Mechanism Of Ductile And Brittleness Of Fe-based Metallic Glasses

Fe-based metallic glasses have excellent properties,but most Fe-based metallic glasses are brittle at room temperature and have low glass formation ability,hindering their widespread use.In this paper,a series of Fe-based metallic glass components were prepared by single roll melt-spinning method and copper mold casting method,the ribbon and bulk samples were prepared,the performance was tested,the toughness and brittleness characteristics were analyzed,and finally the introduction of valence electron concentration,The ductile mechanism of Fe-based metallic glasses was studied.Research shows:(1)Raw material purity and preparation process and other factors have a great influence on the thermal properties of Fe-based metallic glasses.The OTx of prepared Fe77Mo5P9C7.5B1.5 was 74K;the ATx of(Feo.52Co0.3Nio.18)73Cr17Zr10 was 70K;and the ATx of Fe36.5NM35.AP25.3C2.8 was 70K.Based on the bending radius criterion,(Fe0.52Co0.3Ni0.18)73Cri7Zr10,Fe30Co30Ni15Si8B17，Fe77Mo5P9C7.5B,.5,Fe36.5Ni35.4AP25.3C2.8 amorphous ribbons have good bending properties.(2)Select the ribbons with good bending properties,prepared into a wedge-shaped sample,the formation of amorphous critical size:(Feo.52Coo.3Ni0.18)73Cr17Zr10 is 1.8mm;Fe30Co30Ni15Si8Bi7 is 1mm;Fe77Mo5P9C7.5B1.5 between 1～2mm;Fe36.5NM35.AP25.3C2.g is 0.5mm.And the diameter of lmm amorphous rod material was prepared for mechanical testing,measured(Feo.52Coo.3Ni0.18)73Cr17Zr10 yield strength of 2190MPa,breaking strength of 2800MPa,plastic strain of 3.61%,micro-hardness of 954.3HV1;The yield strength of Fe30Co30Ni,5Si8B17 was 2470MPa,the breaking strength was 2600MPa,the plastic strain was 0.3%and the microhardness was 947.6HV1.The yield strength of Fe77Mo5P9C7.5B1.5 was 3100MPa,the breaking strength was 3230MPa and the plastic strain was 0.31%,hardness was 960.5HV1.(3)The valence electron concentration can be used to characterize the ductile and brittleness of Fe-based metallic glasses,and the critical valence electron concentration of ductile-brittle transition is 6.75.With the increase of valence electron concentration,plasticity is enhanced;there is a good quadratic function between valence electron concentration and plastic strain,which satisfies the quadratic equation y=15.95454x2-218.1981 x+747.08539(R2=0.89073,x is valence electron concentration and y is plastic strain).(4)There is a correlation between the valence electron concentration and the thermophysical parameters and the strength of Fe-based metallic glasses.With the increase of valence electron concentration,the glass transition temperature,crystallization temperature and fracture strength all tend to decrease.The glass transition temperature,crystallization temperature and fracture strength of ductile amorphous alloy are lower than that of brittle amorphous alloy.There is a good quadratic relationship between valence electron concentration and plasticity brittleness factor and Poisson’s ratio,respectively satisfying the quadratic equation y=-0.35397x2+4.59183x-14.45655(R2=0.79719,x is valence electron concentration and y is plasticity brittleness factor),y=0.12318x2-1.59182x+5.45285(R2=0.7871,x is the valence electron concentration,y is the Poisson’s ratio).