High-strain-rate nanoindentation behavior of fine-grained magnesium alloys

Somekawa, Hidetoshi; Schuh, Christopher A.

doi:10.1557/jmr.2012.52

Cited by 58 publications

(31 citation statements)

References 37 publications

(45 reference statements)

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“…Nanoindentation can be conducted also with an impact module that allows the utilization of strain rates a few orders of magnitude higher than quasi-static indentation. Contrary to microindentation and nanoindentation, which is established as a standard testing technique when mechanical properties of a material are considered (Rouxel et al, 2010;Limbach et al, 2014;Barlet et al, 2015;Yao et al, 2016), nano-impact testing has, up to now, been applied only in few instances (Beake et al, 2001(Beake et al, , 2009Beake and Smith, 2004;Trelewicz and Schuh, 2008;Jennett and Nunn, 2011;Somekawa and Schuh, 2012;Wheeler and Gunner, 2013). The main problem is probably the natural oscillation of the pendulum during the first impact.…”

Section: Mechanical Testing Of Glassmentioning

confidence: 99%

Influence of Cooling Rate on Cracking and Plastic Deformation during Impact and Indentation of Borosilicate Glasses

et al. 2017

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The influence of a changing glass topology on local mechanical properties was studied in a multitechnique nanomechanical approach. The glass response against sharp contacts can result in structural densification, plastic flow, or crack initiation. By using instrumented indentation testing, the mechanical response was studied in different strain rate regimes for a sodium borosilicate glass (NBS) exhibiting altering structures due to varying processing conditions. Comparison with data from former studies and with literature data on other glass structures helped to elucidate the role of the borate and silicate subnetworks and to understand the overall mechanical properties of the mixed glass systems. A peculiarity of some of the NBS glasses tested in this study is the fact that the connectivity of the borate and silicate entities depends on the sample's thermal history. Although the influence on macroscopic material properties such as E and H is minor, the onset of cracking indeed is influenced by those structural changes within the glass. Rapidly quenched glass shows an improved crack resistance, which is even more pronounced at high strain rates. Studies on various processing conditions further indicate that this transition is closely related to the cooling rate around Tg. The strain rate dependence of cracking is discussed in terms of the occurrence of shear deformation and densification.

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Section: Mechanical Testing Of Glassmentioning

confidence: 99%

Influence of Cooling Rate on Cracking and Plastic Deformation during Impact and Indentation of Borosilicate Glasses

et al. 2017

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“…A tentative Ea ‐value of almost vanishing 5.3 kJ/mol was derived by Li and Jeanloz (). More recently Trelewicz and Schuh () invoked yield stress and creep at constant strain rate and different temperatures for “deformation with dislocation motion.” The corresponding semi‐logarithmic plots with Ni–W alloys and magnesium or its alloys gave Ea values for the indentation (Somekawa and Schuh, ). A difficulty was strong dependences of iterated parameters and for example ill‐defined exponents n from the power‐law creep strain‐rate sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Activation energy of the low-load NaCl transition from nanoindentation loading curves

Kaupp

2014

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Access to activation energies E(a) of phase transitions is opened by unprecedented analyses of temperature dependent nanoindentation loading curves. It is based on kinks in linearized loading curves, with additional support by coincidence of kink and electrical conductivity of silicon loading curves. Physical properties of B1, B2, NaCl and further phases are discussed. The normalized low-load transition energy of NaCl (Wtrans/µN) increases with temperature and slightly decreases with load. Its semi-logarithmic plot versus T obtains activation energy E(a)/µN for calculation of the transition work for all interesting temperatures and pressures. Arrhenius-type activation energy (kJ/mol) is unavailable for indentation phase transitions. The E(a) per load normalization proves insensitive to creep-on-load, which excludes normalization to depth or volume for large temperature ranges. Such phase transition E(a)/µN is unprecedented material's property and will be of practical importance for the compatibility of composite materials under impact and further shearing interactions at elevated temperatures.

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“…More details on the apparatus and analysis are available in Refs. [18,27,28]. These high rate tests were conducted at a variety of temperatures ranging from 300 to 423 K (27 to 150 C).…”

Section: Experimental and Numerical Proceduresmentioning

confidence: 99%

“…Deep trenches are also observed in the upper and lower parts, and all of the specimens measured about 30  45 m 2 . More details on the sample preparation for EBSD observation using FIB are reported in our previous study [18].…”

Section: Experimental and Numerical Proceduresmentioning

confidence: 99%

“…As for magnesium, some indentation results have been reported [15][16][17][18][19][20][21][22][23][24], and the properties from such small scale mechanical tests exhibit some interesting differences from conventional testing using bulk samples, most of which pertain in some way to the multiaxiality of nanoindentation and the necessity of deformation activity in multiple directions in that mode of loading. For example, whereas bulk uniaxial tests using single crystals show strength differences of as much as ten times between basal and non-basal orientations, the difference in indentation depths (indentation hardness) between the basal and non-basal planes at constant load levels is only around 30 % [15].…”

Section: Introductionmentioning

confidence: 99%

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