Effect Of Supercooled Liquid Quenching/Cryogenic Treatment On The Properties Of Ce-and Zr-based Amorphous Alloys

Cryogenic treatment,annealing near the glass transition temperature or quenching treatment is the main method to study the change of the kinetics amorphous materials.The atomic configuration,the internal free volume,and the stability of the variation of energy state of the bulk amorphous alloy after undergoing the above thermal history conditions will change significantly,which will result in changes in the application properties such as alloy strength and plasticity.In the past research work,the thermal history of amorphous alloys is often changed by a certain method,and then the changes of the thermodynamics,kinetic parameters and application properties of the alloy are analyzed.However,there are few reports on the effects of combined treatment on the thermal physical and mechanical properties of bulk amorphous alloys,and the possible mechanism and changes of those properties are not clear enough.Therefore,the effect of combined use of quenching of the supercooled liquid phase and cryogenic treatment on bulk amorphous properties is proposed in this paper.In this paper,rods with 2 mm in diameter of the ternary alloy Ce₇₀Al₁₀Cu₂₀0 and the quarternary alloy Ce₆₉Al₁₀Cu₂₀Co₁ bulk amorphous alloys with a low glass transition temperature were heated to the supercooled liquid area,and then immediately laid them into liquid nitrogen for quenching and simultaneously cryogenic treated.The as-cast and quenched cryogenic samples were tested by universal testing machine and differential scanning calorimetry.The effect of different quenching temperatures?353K,358K,363K and 368K?and different cryogenic time?12h,24h,48h and 96h?on the compressive mechanical properties and kinetics of Ce-based bulk amorphous alloys were analyzed.No crystalline phases were observed except for the ternary amorphous alloy quenched at368K and then cryogenic treatment.The compressive strength of the ternary alloy gradually increases with the quenching temperature and the cryogenic time.The DSC curves show that the glass transition temperature T_g,the crystallization temperature T_x and the enthalpy change?H due to structural relaxation increase with the increase of the cryogenic time at the same quenching temperature,and the time?required for structural relaxation at cryogenic treatment condition decrease with the increasing quenching temperature.By the KWW equation fitting,the limit of enthalpy difference?H^eqafter infinite time of cryogenic treatment at each quenching temperature will tend to be consistent.In addition,the T_g point of the as-cast and quenched cryogenic Ce-based amorphous alloys also increase with increasing heating rate,showing significant kinetic effects.The?relaxation active energy and fragility of the quarternary Ce-based amorphous in the as-cast and quenched cryogenic state were calculated by the Kissinger equation.In addition,the effects of quenching and cryogenic cycle treatment on the microstructure and mechanical properties of Zr-based amorphous with high glass transition temperatures were analyzed.The Zr-based bulk amorphous rods were rapidly heated to the supercooled liquid area for 1 min using a Sn-Zn metal bath,then immediately immersed in liquid nitrogen and cryogenic treatment for 1 min,after which the heating and quenching process were repeated.The results show that the crystalline phases are precipitated in the Zr-based amorphous matrix after quenching and cryogenic cycle.As the number of quenching and cryogenic cycles increases,the volume fraction of crystalline phases increases.After the quenching and cryogenic cycle 2 times,the compressive strength of the sample is slightly higher than that of the as-cast sample,and as the number of cycles continues to increase,the compressive strength of the sample is smaller than that of the as-cast,and it gradually decreases.