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# Judy Pang <pangj@ornl.gov>
# requesting 8 days, at minimum=5 days
# beamline 34ID, "In-situ measurements of local deformation features in polycrystalline Ni"
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# top:/home/www/beamtime-requests/req00381.txt
# UNICAT Member Beam Time Request  #381
# created Fri Mar 14 14:19:50 CST 2003
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beamline:
	34ID

collaboration:
	No

contact:
	pangj@ornl.gov

days:
	8

description:
	Development of the x-ray microbeam diffraction has revolutionized the study of deformation mechanics on the mesoscopic scale. We have started a study of deformation in a polycrystalline Ni sample during various stages of macroscopic deformation. Individual grain rotations, along with sub-grain structures have been measured.  We found that we can relate the sub-grain structures observed in the individual grains to their orientations with respect to the loading axis and with respect to the orientations of their neighboring grains. We have also used differential-aperture microscopy to depth-resolve sub-grain rotations down to 20 mm beneath the sample surface. Early results indicate that deformation features within individual grains, their neighbors, and across grain boundaries are different. It was also found that the rotations of the grains vary as a function of depth and the difference in orientation between the surface and the bulk can be as large as 2%B0.  
	
	We propose an experiment to investigate the variation of deformation features with high spatial resolution around the grain boundaries/junctions. This study will provide the information on the extent of the effects of the grain boundaries with respect to the response of the bulk of the grains. This will also give us insight on the grain size effects as the volume fraction of grain boundaries/junctions increases as grain size decreases. 
	It is estimated measurements over a 5 x 5 x 5 mm3 volume around one triple junction  will take about 2 days. We plan to make measurements on four junctions and  8 beam days will be needed.

equipment+required:
	

experiment:
	In-situ measurements of local deformation features in polycrystalline Ni

foreign+nationals:
	Judy Pang

hazards:
	

minimumdays:
	5

name:
	Judy Pang

new+request:
	on

nonmembers:
	

unacceptable+dates:
	


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