scholarly journals Activation volume details from nonlinear anelastic deformation of a metallic glass

2019 ◽  
Vol 126 (18) ◽  
pp. 185104
Author(s):  
T. J. Lei ◽  
M. Atzmon
2007 ◽  
Vol 1048 ◽  
Author(s):  
Jonathan B. Puthoff ◽  
Donald S. Stone ◽  
Hongbo Cao ◽  
Paul M. Voyles

AbstractWe performed nanoindentation creep experiments on the bulk metallic glass Zr54Cu38Al8 in an effort to measure the scale of the individual deformation events responsible for plastic deformation. From a nanoindentation creep experiment, we can determine V*, the activation volume, which we interpret as the volume of a shear transformation zone (STZ) multiplied by the shear strain undergone by the STZ during thermal activation. For the as-cast alloy hardness, H, is 5.33 ± 0.06 GPa, and V* is 87 ± 5 Å3. The alloy was then annealed near Tg for 24 hr and retested. No crystallization occurred during annealing as verified by XRD and TEM. Following annealing H increased to 7.36 ± 0.08 GPa and V* increased to 160 ± 10 Å3. We interpret the change in V* as arising from an increase in the number of atoms involved in the STZ.


2006 ◽  
Vol 88 (17) ◽  
pp. 171911 ◽  
Author(s):  
A. Concustell ◽  
J. Sort ◽  
A. L. Greer ◽  
M. D. Baró

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 833 ◽  
Author(s):  
Yinghong Chen ◽  
Jichao Qiao

High-temperature deformation around the glass transition temperature Tg and the dynamic mechanical behavior of La30Ce30Al15Co25 metallic glass were investigated. According to dynamic mechanical analysis (DMA) results, La30Ce30Al15Co25 metallic glass exhibits a pronounced slow β relaxation process. In parallel, strain-rate jump experiments around the glass transition temperature were performed in a wide range of strain rate ranges. The apparent viscosity shows a strong dependence on temperature and strain rate, which reflects the transition from non-Newtonian to Newtonian flow. At low strain or high temperature, a transition was observed from a non-Newtonian viscous flow to Newtonian viscous flow. It was found that the activation volume during plastic deformation of La30Ce30Al15Co25 metallic glass is higher than that of other metallic glasses. Higher values of activation volume in La30Ce30Al15Co25 metallic glass may be attributed to existence of a pronounced slow β relaxation. It is reasonable to conclude that slow β relaxation in La30Ce30Al15Co25 metallic glass corresponds to the “soft” regions (structural heterogeneities) in metallic glass.


2015 ◽  
Vol 118 (20) ◽  
pp. 204302 ◽  
Author(s):  
Nicolas Thurieau ◽  
Loïc Perrière ◽  
Mathilde Laurent-Brocq ◽  
Yannick Champion

1985 ◽  
Vol 46 (2) ◽  
pp. 235-241 ◽  
Author(s):  
F. Lançon ◽  
L. Billard ◽  
J. Laugier ◽  
A. Chamberod

2020 ◽  
Author(s):  
Theodosios Famprikis ◽  
O. Ulas Kudu ◽  
James Dawson ◽  
Pieremanuele Canepa ◽  
François Fauth ◽  
...  

<div> <p>Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na<sub>3</sub>PS<sub>4</sub> are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and <i>ab-initio</i> simulations aimed at elucidating the synthesis-property relationships in Na<sub>3</sub>PS<sub>4</sub>. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na<sup>+</sup> migration in Na<sub>3</sub>PS<sub>4</sub>, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na<sub>3</sub>PS<sub>4</sub> to ~10<sup>-4</sup> S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.</p> </div>


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