Browsing by Author "Gokhale, Aditya"

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Characterization of Deformation and Wear Mechanisms During Indentation Scratching on Pure Zinc
(2020-01-01)
Gokhale, Aditya
;
Jain, Jayant
;
Prasad, Rajesh
;
Huang, E-Wen
;
Lee, Soo Yeol
Scratch testing using nanoindentation helps to characterize material's wear resistance and the accompanying material removal, and deformation mechanism. The effect of load and repeated scratching on pure zinc was investigated in this study. Surface examination post scratching revealed the formation of long chips at lower loads, which can be attributed to ductile-like behavior. Ploughing dominated at higher loads, while micro-cutting was active at lower loads. The material removal factor (f(ab)) is an indicator of the prevailing wear mechanism. A good correlation appeared between the observed wear mechanism and the calculated fab, wherein interplay of ploughing and micro-cutting was observed. The decrease in wear rate as the number of passes increased and the decreasing value of fab are indicative of the strain hardening behavior during repeated scratching. The presence of intergranular fracture slip and twinning on the deformed surface is indicative of the material's response to induced stress.
Influence of Zn Addition on Micro-scale Wear of Mg-xZn (x=1-6 wt%) Alloys
(2017-12-01)
Keerti, Shishir
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Gokhale, Aditya
;
Jain, Jayant
;
Huang, E. -Wen
;
材料科學與工程學系
The effect of Zn addition on the scratch-induced wear response of Mg-xZn (x = 1-6 wt%) was investigated. The alloys were studied, at room temperature, for 100 and 400 mN loads in single-pass scratch and continuous scratch mode. Scanning electron microscope and optical profilometer were used to investigate the influence of load and continuous scratching on the wear and deformation mechanisms. The empirical relationships have been proposed to capture the dependence of wear rate on Zn concentration. For dilute Mg-Zn alloy, the wear rate was found to be more concentration dependent than the concentrated alloys. This was attributed to the softening effect of Zn on the non-basal slip systems. Additionally, the role of Zn solute in affecting the strain-hardening behaviour during continuous scratching has been discussed.
Nanowear Mechanisms of Mg Alloyed with Al and Y at Elevated Temperatures
(2020-03-03)
Gokhale, Aditya
;
Meena, Trapesh
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Lee, Soo Yeol
;
Huang, E-Wen
;
Gosvami, Nitya N.
We examine the role of important alloying elements (Al, Y), on friction and wear mechanisms of Mg as a function of temperature. Friction and wear tests of Mg-5%Al and Mg-5%Y alloys performed at room temperature, 100 degrees C and 150 degrees C reveal that addition of Al and Y significantly reduces the coefficient of friction. However, despite higher hardness of Mg-5%Y alloy, its wear rate was found to be higher than Mg-5%Al alloy at elevated temperatures. We show that this behaviour, observed for Mg-5%Y alloy at elevated temperature, can be attributed to its higher surface energy than Mg-5%Al and pure Mg, leading to enhanced adhesive wear, which is detrimental to tribological applications.
Quantitative evaluation of grain boundary sliding and its dependence on orientation and temperature in pure Zn
(2019-07-01)
Gokhale, Aditya
;
Sarvesha, R.
;
Huang, E-Wen
;
Lee, Soo Yeol
;
Prasad, Rajesh
In the present work, grain boundary sliding (GBS) has been studied for the grains exhibiting different orientations (for indentation parallel and perpendicular to < c > axis) at different temperatures (RT to 200 degrees C) using nanoindentation in pure Zn. Electron back scattered diffraction was utilized to determine the orientation of the indented grains and identify the deformation mechanism, whereas atomic force microscopy was utilized to systematically quantify the GBS. Results indicated that indentation perpendicular to < c > axis exhibits slip induced GBS, whereas the indentation parallel to < c > axis results in pure GBS. The amount of GBS was also found to be strongly dependent upon the orientation of the neighboring grain. Further, the contribution from GBS towards total stain was found to increase with an increase in temperature. (C) 2019 Elsevier B.V. All rights reserved.