Field strength effect on elastoplastic behavior of aluminoborosilicate glass: II. Volumetric recovery

Abstract

The field strength (FS) effect of six different network modifiers on the elastoplastic properties of aluminoborosilicate glasses was explored using a volumetric recovery study. This work, in conjunction with Part I, explored the intersection of hardness, crack resistance, and other physical properties with glass elasticity. Results showed that (1) the elastic volume fraction decreased with FS for both the alkali and alkaline earth (AE) glasses; (2) the Poisson's ratio did not trend with pile‐up or shear flow volume fraction; (3) the elastic‐to‐plastic deformation ratio increased with applied load and decreased with modifier FS for both the alkali and AE glasses; and (4) an increase in plasticity correlated with increased hardness, crack resistance, and elastic moduli.

Fracture toughness of Ca‐, Sr‐, and Ba‐aluminoborosilicate glasses

“…13 Regardless, the connectivity of a glass network is intimately related to mechanical properties of a glass, adapting under both thermal and mechanical stresses. 14 Previous work has found that hardness, crack resistance, 15 elastic moduli, 16 and plasticity 17 have all increased as modifier FS was increased in the current ABS compositions. It was posited that the observed increase in hardness and elastic moduli as a function of increasing NWM-FS was due to increased atomic packing density (decreased molar volume) as a result of increased NWM-oxygen bond strength (i.e., shortened NWM-O bond length).…”

“…The same batch compositions (in mole percent), as well as melting and annealing temperatures, were used to synthesize all AE-ABS glasses for the current and previous studies. More details regarding glass design and synthesis are given in the previous work, [15][16][17] and more material properties are provided in Appendix A.…”

“…For example, the value for f•E/H is the lowest for materials with ring and cone cracking during the loading half-cycle. Since the present compositions are prone to densification, 17 and there is no non-numerical way to determine f, the elastoplastic ratio (H/E) as defined by Lawn and Howes 38 will be employed here. Lawn and Howes concluded that materials can be categorized along an elastic-plastic spectrum, where a material is considered an ideal elastic when…”

“…The elastoplastic ratio was calculated directly from E and Vickers hardness data. The residual impression parameter (RP) was calculated using Vickers imprint data (F = 1.0 kgf) from previous work 17 and γ was determined by fitting RP to Equation (8).…”

“…15,16 Previous work also found an increase in plasticity as a function of NWM FS, likely due to higher FS modifiers having higher mobility under an applied stress, which could explain the historically contradictory increase in both hardness and crack resistance. 17 This paper focuses on the three best performing compositions, Ca-, Sr-, and Ba-ABS, to examine whether the apparent FS effect is observed with fracture toughness and brittleness.…”