TY - JOUR
T1 - Hardness and incipient plasticity in silicate glasses
T2 - Origin of the mixed modifier effect
AU - Kjeldsen, Jonas
AU - Smedskjaer, Morten M.
AU - Mauro, John C.
AU - Yue, Yuanzheng
N1 - Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2014/2/3
Y1 - 2014/2/3
N2 - The scaling of Vickers hardness (Hv) in oxide glasses with varying network modifier/modifier ratio is manifested as either a positive or negative deviation from linearity with a maximum deviation at the ratio of about 1:1. In an earlier study [J. Kjeldsen et al., J. Non-Cryst. Solids 369, 61 (2013)], we observed a minimum of Hv in CaO/MgO sodium aluminosilicate glasses at CaO/MgO = 1:1 and postulated that this minimum is linked to a maximum in plastic flow. However, the origin of this link has not been experimentally verified. In this work, we attempt to do so by exploring the links among Hv, volume recovery ratio (VR) and plastic deformation volume (VP) under indentation, glass transition temperature (Tg), Young's modulus (E), and liquid fragility index (m) in CaO/MgO and CaO/Li2O sodium aluminosilicate glasses. We confirm the negative deviations from linearity and find that the maximum deviation (i.e., the so-called mixed modifier effect) of Hv, Tg, and m is at the modifier ratio of 1:1. These deviations increase in intensity as the total modifier concentration increases. We find a strong correlation between VP and Hv for the CaO/MgO series, implying that the minimum in Hv originates primarily from an increased shear flow in the mixed modifier glasses.
AB - The scaling of Vickers hardness (Hv) in oxide glasses with varying network modifier/modifier ratio is manifested as either a positive or negative deviation from linearity with a maximum deviation at the ratio of about 1:1. In an earlier study [J. Kjeldsen et al., J. Non-Cryst. Solids 369, 61 (2013)], we observed a minimum of Hv in CaO/MgO sodium aluminosilicate glasses at CaO/MgO = 1:1 and postulated that this minimum is linked to a maximum in plastic flow. However, the origin of this link has not been experimentally verified. In this work, we attempt to do so by exploring the links among Hv, volume recovery ratio (VR) and plastic deformation volume (VP) under indentation, glass transition temperature (Tg), Young's modulus (E), and liquid fragility index (m) in CaO/MgO and CaO/Li2O sodium aluminosilicate glasses. We confirm the negative deviations from linearity and find that the maximum deviation (i.e., the so-called mixed modifier effect) of Hv, Tg, and m is at the modifier ratio of 1:1. These deviations increase in intensity as the total modifier concentration increases. We find a strong correlation between VP and Hv for the CaO/MgO series, implying that the minimum in Hv originates primarily from an increased shear flow in the mixed modifier glasses.
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U2 - 10.1063/1.4864400
DO - 10.1063/1.4864400
M3 - Article
AN - SCOPUS:84899805643
SN - 0003-6951
VL - 104
JO - Applied Physics Letters
JF - Applied Physics Letters
IS - 5
M1 - 051913
ER -