Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature
Abstract Virtual melting (VM) as alternative deformation and stress relaxation mechanisms under extreme load is directly validated by molecular dynamics (MD) simulations of the simple shear of single crystal Si I at a temperature 1383 K below the melting temperature. The shear band consisting of liq...
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-03-01
|
| Series: | npj Computational Materials |
| Online Access: | https://doi.org/10.1038/s41524-025-01537-1 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850027995459223552 |
|---|---|
| author | Hao Chen Valery I. Levitas |
| author_facet | Hao Chen Valery I. Levitas |
| author_sort | Hao Chen |
| collection | DOAJ |
| description | Abstract Virtual melting (VM) as alternative deformation and stress relaxation mechanisms under extreme load is directly validated by molecular dynamics (MD) simulations of the simple shear of single crystal Si I at a temperature 1383 K below the melting temperature. The shear band consisting of liquid Si is formed immediately after the shear instability while stresses drop to zero. This process is independent of the applied shear rate. A new thermodynamic approach is developed, and the thermodynamic criterion for VM, which depends on the ratio of the sample to shear band widths, is derived analytically and confirmed by MD simulations. Since stress-free melt is unstable at 300 K, with further shear, the VM immediately transforms to a mixture of low-density amorphous a-Si, stable Si I, and metastable Si IV. Cyclic transformations between a-Si ↔ Si I, a-Si ↔ Si IV, and Si I ↔ Si IV with volume fraction of all phases mostly between 0.2 and 0.4 and non-repeatable nanostructure evolution are reveled. Such cyclic transformations produce additional important carriers for plastic deformation through transformation strain and transformation-induced plasticity due to volume change, which may occur in shear bands in various material systems but missed in experiments and simulations. The release of shear stresses quenches the microstructure, and shows reasonable qualitative correspondence with existing experiments. |
| format | Article |
| id | doaj-art-670ca372d6804a6db9b02a0c28c411d3 |
| institution | DOAJ |
| issn | 2057-3960 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Computational Materials |
| spelling | doaj-art-670ca372d6804a6db9b02a0c28c411d32025-08-20T02:59:57ZengNature Portfolionpj Computational Materials2057-39602025-03-0111111010.1038/s41524-025-01537-1Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperatureHao Chen0Valery I. Levitas1School of Mechanical Engineering, Jiangsu UniversityIowa State University, Departments of Aerospace Engineering and Mechanical EngineeringAbstract Virtual melting (VM) as alternative deformation and stress relaxation mechanisms under extreme load is directly validated by molecular dynamics (MD) simulations of the simple shear of single crystal Si I at a temperature 1383 K below the melting temperature. The shear band consisting of liquid Si is formed immediately after the shear instability while stresses drop to zero. This process is independent of the applied shear rate. A new thermodynamic approach is developed, and the thermodynamic criterion for VM, which depends on the ratio of the sample to shear band widths, is derived analytically and confirmed by MD simulations. Since stress-free melt is unstable at 300 K, with further shear, the VM immediately transforms to a mixture of low-density amorphous a-Si, stable Si I, and metastable Si IV. Cyclic transformations between a-Si ↔ Si I, a-Si ↔ Si IV, and Si I ↔ Si IV with volume fraction of all phases mostly between 0.2 and 0.4 and non-repeatable nanostructure evolution are reveled. Such cyclic transformations produce additional important carriers for plastic deformation through transformation strain and transformation-induced plasticity due to volume change, which may occur in shear bands in various material systems but missed in experiments and simulations. The release of shear stresses quenches the microstructure, and shows reasonable qualitative correspondence with existing experiments.https://doi.org/10.1038/s41524-025-01537-1 |
| spellingShingle | Hao Chen Valery I. Levitas Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature npj Computational Materials |
| title | Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature |
| title_full | Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature |
| title_fullStr | Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature |
| title_full_unstemmed | Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature |
| title_short | Virtual melting and cyclic transformations between amorphous Si, Si I, and Si IV in a shear band at room temperature |
| title_sort | virtual melting and cyclic transformations between amorphous si si i and si iv in a shear band at room temperature |
| url | https://doi.org/10.1038/s41524-025-01537-1 |
| work_keys_str_mv | AT haochen virtualmeltingandcyclictransformationsbetweenamorphoussisiiandsiivinashearbandatroomtemperature AT valeryilevitas virtualmeltingandcyclictransformationsbetweenamorphoussisiiandsiivinashearbandatroomtemperature |