####################################################
# Judy Pang <pangj@ornl.gov>
# requesting 8 days, at minimum=6 days
# beamline 34ID-E, Crack propagation of Al/Al2O3 composite
# instrument 34ID-E microbeam
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# top:/home/www/beamtime-requests/req00535.txt
# UNICAT Member Beam Time Request  #535
# created Wed Dec 10 15:03:34 CST 2003
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beamline:
	34ID-E

collaboration:
	No

collaborator_Wenjun:
	ON

contact:
	pangj@ornl.gov

days:
	8

description:
	The proposed experiment is part of the ongoing effort to study the fracture mechanism of metal matrix composite system. Fracture toughness in composites is largely affected by the load partitioning between the matrix and the reinforced phases. Measurements on a simple composite system composed of a single crystal Al sandwiched by sapphire single crystal ceramics have been made. The strain profile introduced due to the mismatch of the thermal expansion coefficients was found. The results indicated that the spatial and the angular resolutions of the microbeam technique are suitable for fracture investigation. The resistance to fracture is contributed primarily by the constrained plastic deformation of the ductile Al phase. Finite element calculation based on Gurson constitutive equations has been reported to account for the fracture mechanism of the system. The essential information to check the validity of these calculations is the stress field and hydrostatic stress in the crack tip field. 

In this proposed experiment, Al/Al2O3 samples will be made with crack initiated across both the Al2O3 layers held by the thin Al layer. The strain shared among the two phases as the crack propagates under load will be probed. Strain measurements on this system required the differential aperture technique. Estimated time required to complete one series of loading experiment on a fractured sample is about 8 days.

equipment_required:
	

experiment:
	Crack propagation of Al/Al2O3 composite

foreign_nationals:
	Judy Pang

hazards:
	

instrument:
	34ID-E microbeam

instrument_other:
	

minimumdays:
	6

name:
	Judy Pang

nonmembers:
	Joachim Schneibel (ORNL)
Paul Becher (ORNL)

unacceptable_dates:
	January and February.

z34ID_change_undulator:
	yes

z34ID_details:
	Dedicated beamtime will allow us to arrange the instrumental setting ideal for the measurements and monochromatic energy scan for strain determination will be made possible.

z34ID_on_axis:
	no

z34ID_parasitic:
	yes

z34ID_taper:
	no


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