IMECH-IR  > 非线性力学国家重点实验室
On the origin of softening in the plastic deformation of metallic glasses
Zhang M1,2; Chen Y(陈艳)2,3; Li W1
Corresponding AuthorZhang, M.(m.zhangiwrm@jnu.edu.cn)
Source PublicationINTERNATIONAL JOURNAL OF PLASTICITY
2019-05-01
Volume116Pages:24-38
ISSN0749-6419
AbstractIn the plastic deformation of amorphous materials, dilatation occurs universally with softening. However, the critical question that whether softening is caused by dilatation or not remains an ansatz and requires experimental examination. In this work, by examining the deformation behaviors of 3 metallic glasses (MGs) with distinct Johari-Goldstein (JG) relaxation characteristics before and after crystallization with nanoindentation, it is found that the origin of softening is probably not dilatation but the collective mode in the activation dynamics of shear transformation zones (STZs). Since the deformation in the creep stage of nanoindentation of the MGs originates from the "delayed plasticity" from the loading stage and depends on the softened deforming state of the MGs, the creep depth vs. time curves in the creep stage of nanoindentation of the MGs are examined and display similar loading rate dependent softening phenomena for both the glassy and crystallized MGs. The stretched exponent and relaxation time characterizing the deformation dynamics in the creep stage of nanoindentation are derived by fitting the creep depth vs. time curves with the Kohlrausch-Williams-Watts (KWW) equation. The stretched exponents indicate similar collective modes in the activation dynamics of the elementary deformation units (STZs in glassy MGs and dislocations in crystallized MGs). The relaxation times manifest similar softening effects in the deformation accommodation processes of both the glassy and crystallized MGs, except for a glassy La MG of which the relaxation time is extraordinary for its pronounced JG relaxation. The extraordinary relaxation time of the glassy La MG precludes the possibility of shear dilatation being the main cause for the softening of the glassy La MGs indicated by the loading rate dependent creep depth vs. time curves. The stretched exponent and the relaxation time indicate the homological softening dynamics in the plastic deformation of the glassy and crystallized MGs. For the distinct elementary deformation units, i.e., STZs in glassy MGs and dislocations in crystallized MGs, noting the absence of dilatation in dislocation movements, the softening phenomena in the plastic deformation of both the glassy and crystallized MGs is suggested to originate from the collective mode in the activation dynamics of the elementary deformation units, rather than from local properties of elementary deformation units, such as dilatation in STZs.
KeywordMetallic glass Softening Nanoindentation Structural relaxation
DOI10.1016/j.ijplas.2018.12.004
Indexed BySCI ; EI
Language英语
WOS IDWOS:000463303400002
WOS KeywordNANOINDENTATION CREEP-BEHAVIOR ; SERRATED FLOW ; INSTRUMENTED INDENTATION ; RATE DEPENDENCE ; RELAXATION ; TEMPERATURE ; NANOCRYSTALLINE ; INSTABILITY ; ROOM ; COMPRESSION
WOS Research AreaEngineering ; Materials Science ; Mechanics
WOS SubjectEngineering, Mechanical ; Materials Science, Multidisciplinary ; Mechanics
Funding ProjectNational Nature and Science Foundation of China[51701082] ; Fundamental Research Funds for the Central Universities ; Guangdong Province Science and Technology Plan[2017B090903005] ; Opening Fund of State Key Laboratory of Non-linear Mechanics[LNM201812]
Funding OrganizationNational Nature and Science Foundation of China ; Fundamental Research Funds for the Central Universities ; Guangdong Province Science and Technology Plan ; Opening Fund of State Key Laboratory of Non-linear Mechanics
Classification一类
Ranking2
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Document Type期刊论文
Identifierhttp://dspace.imech.ac.cn/handle/311007/78715
Collection非线性力学国家重点实验室
Affiliation1.Jinan Univ, Inst Adv Wear & Corros Resistant & Funct Mat, Guangzhou 510632, Guangdong, Peoples R China;
2.Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China;
3.Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
Zhang M,Chen Y,Li W. On the origin of softening in the plastic deformation of metallic glasses[J]. INTERNATIONAL JOURNAL OF PLASTICITY,2019,116:24-38.
APA Zhang M,陈艳,&Li W.(2019).On the origin of softening in the plastic deformation of metallic glasses.INTERNATIONAL JOURNAL OF PLASTICITY,116,24-38.
MLA Zhang M,et al."On the origin of softening in the plastic deformation of metallic glasses".INTERNATIONAL JOURNAL OF PLASTICITY 116(2019):24-38.
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