Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy

Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy

Bibliographic Details
Main Author: Pakiru, Swapna
Language:English
Published: Cleveland State University / OhioLINK 2011
Subjects:
Chemical Engineering
Materials Science
Metallurgy
Directional Solidification
Step change
Growth Speed
Morphology
Nearest Neighbor Spacing
Trunk diameter
Side branch length
Side branch orientation
Al- 7 wt% Si alloy
thermal gradient
step increase
step decrease
steady state
transition.
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=csu1323970093
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-csu13239700932021-08-03T05:35:19Z Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy Pakiru, Swapna Chemical Engineering Materials Science Metallurgy Directional Solidification Step change Growth Speed Morphology Nearest Neighbor Spacing Trunk diameter Side branch length Side branch orientation Al- 7 wt% Si alloy thermal gradient step increase step decrease steady state transition. <p>Dendritic single crystals of Al-7wt%Si alloy have been directionally solidified at a thermal gradient of 40 K cm-1 over growth speeds, ranging from 5 to 85 to 31µm s-1, using aluminum single crystal seed aligned along [100] crystallographic orientation. Mushy zone morphology parameters, such as, primary dendrite nearest neighbor spacing, primary dendrite trunk diameter, side (secondary dendrite) branch length and side branch orientation, have been characterized in to investigate the transients introduced by step increase and step decrease in growth speed. </p><p>An increase in the growth speed shows a decrease in both nearest neighbor spacing and trunk diameter. A comparison between the two parameters suggests that the trunk-diameter may be a better metric to quantify differences due to small change in processing parameters, such as, growth in low-gravity in the absence of convection. The trend of decreasing trunk diameter with increasing growth speed is similar to the primary dendrite tip radii trend (predicted by theoretical models). Statistical analysis of the transverse microstructures after the step decrease in growth speed (from 85 to 31µm s-1) showed that primary dendrites which survive the transient are the ones with larger neighbor spacing. However, the predictive ability of nearest-neighbor distance (NNS-1), mean of four nearest neighbor distances (NNS-4) or the mean of six nearest neighbor distances (NNS-6) in terms of which dendrites are likely to dissolve-off appears to be similar. Average side-branch length of the surviving primary dendrites increases and those of the disappearing primary dendrites decreases after the growth speed decrease. Primary dendrites whose side-arms are not orthogonal are more likely to dissolve-off than those which are aligned closer to [100]. Porosity formation during directional solidification can lead to spurious grain formation which will seriously degrade the high temperature creep properties of directionally solidified components.</p> 2011 English text Cleveland State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=csu1323970093 http://rave.ohiolink.edu/etdc/view?acc_num=csu1323970093 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Chemical Engineering
Materials Science
Metallurgy
Directional Solidification
Step change
Growth Speed
Morphology
Nearest Neighbor Spacing
Trunk diameter
Side branch length
Side branch orientation
Al- 7 wt% Si alloy
thermal gradient
step increase
step decrease
steady state
transition.
spellingShingle Chemical Engineering
Materials Science
Metallurgy
Directional Solidification
Step change
Growth Speed
Morphology
Nearest Neighbor Spacing
Trunk diameter
Side branch length
Side branch orientation
Al- 7 wt% Si alloy
thermal gradient
step increase
step decrease
steady state
transition.
Pakiru, Swapna
Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
author Pakiru, Swapna
author_facet Pakiru, Swapna
author_sort Pakiru, Swapna
title Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
title_short Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
title_full Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
title_fullStr Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
title_full_unstemmed Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy
title_sort effect of step change in growth speed during directional solidification on array morphology of al-7 wt% si alloy
publisher Cleveland State University / OhioLINK
publishDate 2011
url http://rave.ohiolink.edu/etdc/view?acc_num=csu1323970093
work_keys_str_mv AT pakiruswapna effectofstepchangeingrowthspeedduringdirectionalsolidificationonarraymorphologyofal7wtsialloy
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