Dynamic mechanical relaxation processes,particularly secondary relaxation processes,are closely related to the mechanical and physical properties of metallic glasses.Here the effect of oscillation strain amplitude on ...Dynamic mechanical relaxation processes,particularly secondary relaxation processes,are closely related to the mechanical and physical properties of metallic glasses.Here the effect of oscillation strain amplitude on the secondary relaxation of a typical Labased metallic glass was studied using the dynamic mechanical analysis method.The apparent activation energy of theβrelaxation is shown to increase with the oscillation strain amplitude.When it changes from 0.02%to 0.16%,the activation energy increases from 0.73 to 0.96 eV.Simultaneously,the intensity of theβrelaxation shifts toward high temperature.Additionally,the apparentβrelaxation is found to be sensitive to the physical aging below the glass transition temperature.The findings suggest a correlation between the inelastic deformation and the relaxation behavior of amorphous metals.展开更多
Structural rejuvenation is vital and attractive for modulating the energetic state and structural heterogeneity of bulk metallic glasses(BMGs). In this paper, we show that cooling a BMG from a supercooled liquid regio...Structural rejuvenation is vital and attractive for modulating the energetic state and structural heterogeneity of bulk metallic glasses(BMGs). In this paper, we show that cooling a BMG from a supercooled liquid region at laboratory rates can reverse the relaxation enthalpy lost during the preceding structural relaxation. Increasing the cooling rate is beneficial for enhancing atomic mobility and dynamic mechanical relaxation intensity. Therefore, this rejuvenation methodology promotes tailoring the mechanical properties of BMGs and provides a comprehensive understanding of the rejuvenation mechanism.展开更多
Bulk metallic glasses(BMGs)represent a class of solid materials which have randomly packed atomic structure in long range but exhibit unique properties.Nowadays,the macroscopic brittleness at ambient temperature is th...Bulk metallic glasses(BMGs)represent a class of solid materials which have randomly packed atomic structure in long range but exhibit unique properties.Nowadays,the macroscopic brittleness at ambient temperature is the fundamental and intriguing issue to impede the engineering application of BMGs.In this article,we report a breakthrough in solving the strength-ductility tradeoff dilemma of BMGs by introducing strong forced vibration of atoms named ultrasonic vibration(USV)technique.We find that not only the ambient temperature compressive plasticity is remarkably increased but also yield strength is augmented by kHZ level USV treatment.The toughening of BMGs has also been evidenced by the pronounced increase in the first pop-in event,which represents by the critical stress to stimulate the initial yield with the formation of shear band.It has also been confirmed that the free volume in USV treated BMGs is strikingly increased.Therefore,the intrinsic mechanism of USV induced toughening can be interpreted in the frame of structural heterogeneities and energy landscape theory,i.e.,the USV induced structural rejuvenation by increasing the loosely packed soft regions and decreasing the closely packed hard regions.The basins that possess larger potential energies are overwhelmingly increased after USV treatment.Our findings provide a new approach for surmounting strength-ductility trade-off dilemma of single atom glassy matter such as BMGs.展开更多
基金Investigación Financiado por MCIN/AEI/10.13039/501100011033 (Proyecto PID2020-112975GB-I00)Generalitat de Catalunya AGAUR (2017-SGR-42)+3 种基金Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (CX202031)supported by China Scholarship Council (202006290092, 202206290063)National Natural Science Foundation of China (51971178, 52271153)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province (2021JC12)。
基金supported by the National Natural Science Foundation of China(Grant Nos.51971178 and 52271153)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(Grant No.2021JC-12)+4 种基金the Natural Science Foundation of Chongqing(Grant No.cstc2020jcyj-jq X0001)financial support from“Proyecto PID2020-112975GB-I00 de investigación financiado por MCIN/AEI/10.13039/501100011033”Generalitat de Catalunya AGAUR 2021-SGR-343 grantsupported by the National Natural Science Foundation of China(Grant No.12072344)the Youth Innovation Promotion Association of the Chinese Academy of Sciences。
文摘Dynamic mechanical relaxation processes,particularly secondary relaxation processes,are closely related to the mechanical and physical properties of metallic glasses.Here the effect of oscillation strain amplitude on the secondary relaxation of a typical Labased metallic glass was studied using the dynamic mechanical analysis method.The apparent activation energy of theβrelaxation is shown to increase with the oscillation strain amplitude.When it changes from 0.02%to 0.16%,the activation energy increases from 0.73 to 0.96 eV.Simultaneously,the intensity of theβrelaxation shifts toward high temperature.Additionally,the apparentβrelaxation is found to be sensitive to the physical aging below the glass transition temperature.The findings suggest a correlation between the inelastic deformation and the relaxation behavior of amorphous metals.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51971178 and 52271153)financially supported by National Natural Science Foundation of China (Grant No. 12072344)+4 种基金the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(Grant No. 2021JC-12)the Natural Science Foundation of Chongqing(Grant No. cstc2020jcyj-jq X0001)sponsored by the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (Grant No. CX2021015)the Youth Innovation Promotion Association of the Chinese Academy of Sciencesfinancial support from Research Grant Council (RGC) and the Hong Kong government through the General Research Fund (GRF)(Grant Nos.U11200719 and U11213118)。
文摘Structural rejuvenation is vital and attractive for modulating the energetic state and structural heterogeneity of bulk metallic glasses(BMGs). In this paper, we show that cooling a BMG from a supercooled liquid region at laboratory rates can reverse the relaxation enthalpy lost during the preceding structural relaxation. Increasing the cooling rate is beneficial for enhancing atomic mobility and dynamic mechanical relaxation intensity. Therefore, this rejuvenation methodology promotes tailoring the mechanical properties of BMGs and provides a comprehensive understanding of the rejuvenation mechanism.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51922089,51972275,51871185,51727803&51872241)the Key Research Plan in Shanxi Province(Grant No.2018GY-104).
文摘Bulk metallic glasses(BMGs)represent a class of solid materials which have randomly packed atomic structure in long range but exhibit unique properties.Nowadays,the macroscopic brittleness at ambient temperature is the fundamental and intriguing issue to impede the engineering application of BMGs.In this article,we report a breakthrough in solving the strength-ductility tradeoff dilemma of BMGs by introducing strong forced vibration of atoms named ultrasonic vibration(USV)technique.We find that not only the ambient temperature compressive plasticity is remarkably increased but also yield strength is augmented by kHZ level USV treatment.The toughening of BMGs has also been evidenced by the pronounced increase in the first pop-in event,which represents by the critical stress to stimulate the initial yield with the formation of shear band.It has also been confirmed that the free volume in USV treated BMGs is strikingly increased.Therefore,the intrinsic mechanism of USV induced toughening can be interpreted in the frame of structural heterogeneities and energy landscape theory,i.e.,the USV induced structural rejuvenation by increasing the loosely packed soft regions and decreasing the closely packed hard regions.The basins that possess larger potential energies are overwhelmingly increased after USV treatment.Our findings provide a new approach for surmounting strength-ductility trade-off dilemma of single atom glassy matter such as BMGs.
