Bulk ultrafine grained/nanocrystalline metals via slow cooling

Chezheng Cao; Gongcheng Yao; Lin Jiang; Maximilian Sokoluk; Xin Wang; Jim Ciston; Abdolreza Javadi; Zeyi Guan; Igor De Rosa; Weiguo Xie; Enrique J Lavernia; Julie M Schoenung; Xiaochun Li

doi:10.1126/sciadv.aaw2398

Bulk ultrafine grained/nanocrystalline metals via slow cooling

Sci Adv. 2019 Aug 23;5(8):eaaw2398. doi: 10.1126/sciadv.aaw2398. eCollection 2019 Aug.

Authors

Chezheng Cao^{1

2}, Gongcheng Yao^{1

2}, Lin Jiang^{3

4}, Maximilian Sokoluk², Xin Wang³, Jim Ciston⁵, Abdolreza Javadi², Zeyi Guan², Igor De Rosa¹, Weiguo Xie⁶, Enrique J Lavernia³, Julie M Schoenung³, Xiaochun Li^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
² Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
³ Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA 96297, USA.
⁴ Materials & Structural Analysis, Thermo Fisher Scientific, Hillsboro, OR 97124, USA.
⁵ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁶ Camborne School of Mines, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.

Abstract

Cooling, nucleation, and phase growth are ubiquitous processes in nature. Effective control of nucleation and phase growth is of significance to yield refined microstructures with enhanced performance for materials. Recent studies reveal that ultrafine grained (UFG)/nanocrystalline metals exhibit extraordinary properties. However, conventional microstructure refinement methods, such as fast cooling and inoculation, have reached certain fundamental limits. It has been considered impossible to fabricate bulk UFG/nanocrystalline metals via slow cooling. Here, we report a new discovery that nanoparticles can refine metal grains to ultrafine/nanoscale by instilling a continuous nucleation and growth control mechanism during slow cooling. The bulk UFG/nanocrystalline metal with nanoparticles also reveals an unprecedented thermal stability. This method overcomes the grain refinement limits and may be extended to any other processes that involve cooling, nucleation, and phase growth for widespread applications.