<p>Metals in advanced nuclear reactors, such as W, often experience microcracks. However, the synergistic effects of high temperature, stress, and specialized structures can improve the self-healing ability of these metals. Microcrack healing is closely related to crack surface conditions. The order and disorder degree of crack surface atoms may affect crack stability. In this study, first-principles calculations, ab initio molecular dynamics, and surface thermodynamic theory were used to investigate the stability of grain boundary (GB) cracks at 0, 293, and 373 K. We compared the energy densities, crack attraction energies, and atomic diffusion behaviors of crack surfaces at <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1689_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="64" /> </InlineMediaObject> <EquationSource Format="TEX">$\sum {3}\,\hbox {GBs}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>∑</mo> <mn>3</mn> <mspace width="0.166667em" /> <mtext>GBs</mtext> </mrow> </math></EquationSource> </InlineEquation> with those at <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1689_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="64" /> </InlineMediaObject> <EquationSource Format="TEX">$\sum5\, \hbox {GBs}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>∑</mo> <mn>5</mn> <mspace width="0.166667em" /> <mtext>GBs</mtext> </mrow> </math></EquationSource> </InlineEquation>. Adsorption on the nanocrack surface determines the critical nanocrack width. It was found that Al <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1689_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="68" /> </InlineMediaObject> <EquationSource Format="TEX">$\sum \hbox {3(111)}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>∑</mo> <mtext>3(111)</mtext> </mrow> </math></EquationSource> </InlineEquation> nanocracks heal at high temperatures, and this healing behavior is closely related to the crack surface energy. Meanwhile, the GB cracks of W heal in an orderly manner at 573 and 1203 K. BY contrast, the GB cracks of Ti remain unhealed. Finally, a high-temperature nanocrack expansion model was developed and used to predict crack behavior under applied stress at different temperatures.</p>

Study on the healing mechanism of nanograin boundary cracks in Al, W, and Ti

期刊论文
发表日期：

2025年5月8日

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Jun Hui,
Xiao-Yong Zhang,
Jia-Peng Chen,
Bin Chen,
Min Liu,
Biao Wang

摘要

Metals in advanced nuclear reactors, such as W, often experience microcracks. However, the synergistic effects of high temperature, stress, and specialized structures can improve the self-healing ability of these metals. Microcrack healing is closely related to crack surface conditions. The order and disorder degree of crack surface atoms may affect crack stability. In this study, first-principles calculations, ab initio molecular dynamics, and surface thermodynamic theory were used to investigate the stability of grain boundary (GB) cracks at 0, 293, and 373 K. We compared the energy densities, crack attraction energies, and atomic diffusion behaviors of crack surfaces at $\sum {3}\,\hbox {GBs}$ $\sum 3 GBs$ with those at $\sum5\, \hbox {GBs}$ $\sum 5 GBs$ . Adsorption on the nanocrack surface determines the critical nanocrack width. It was found that Al $\sum \hbox {3(111)}$ $\sum 3(111)$ nanocracks heal at high temperatures, and this healing behavior is closely related to the crack surface energy. Meanwhile, the GB cracks of W heal in an orderly manner at 573 and 1203 K. BY contrast, the GB cracks of Ti remain unhealed. Finally, a high-temperature nanocrack expansion model was developed and used to predict crack behavior under applied stress at different temperatures.