Anomalous size effects in nanoporous materials induced by high surface energies. Issue 13 (15th July 2019)

• Record Type: Journal Article
• Authors: Wilkerson, Justin W.
• Is Part Of: Journal of materials research. Volume 34:Issue 13(2019)
• Page Start: 2337
• Page End: 2346
• Publication Date: 2019-07-15
• Subjects: nanoscale, -- nanostructure, -- strength; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1557/jmr.2019.100
• Languages: English
• ISSNs: 0884-2914

Abstract

Abstract: Abstract : Several experiments and molecular dynamics calculations have reported anomalous mechanical behaviors of nanoporous materials that may be attributed to capillary effects. For example, nanoporous gold exhibits a tension–compression asymmetry in yield strength with the material being stronger in compression than tension. In addition, some molecular dynamics calculations have reported a spontaneous collapse of pores in nanoporous gold with nanometer-sized ligaments. Despite these perplexing observations, there are few theoretical models capable of shedding light on such capillary phenomena, particularly under general stress states. Here, we utilize a physics-based model to explore the implications of high surface energies on the mechanical response of dislocation-starved nanoporous materials subject to general stress states. For low stress triaxialities, we report an anomalous size effect and an anomalous temperature-dependence of dislocation-starved nanoporous materials with sufficiently large surface energies. Additionally, we provide an analytic criterion for spontaneous pore collapse in nanoporous materials with nanometer-sized ligaments.