Fluid Mechanics of Freckle Formation in Directionally       Solidified Alloys
{'Code': '07020000', 'Directorate': {'Abbreviation': 'ENG', 'LongName': 'Directorate For Engineering'}, 'Division': {'Abbreviation': 'CBET', 'LongName': 'Div Of Chem, Bioeng, Env, & Transp Sys'}}
{'SignBlockName': 'HUSEYIN A. SEHITOGLU', 'PO_EMAI': None, 'PO_PHON': None}
Directional solidification is a process in which an alloy melt is               solidified by cooling from the bottom of the mold.  In the resulting            casting, the grain boundaries transverse to the solidification                  direction are virtually eliminated.  The material thus obtained shows           increased creep rupture strain and improved thermal fatigue behavior,           two important characteristics for the modern gas turbine blades.  It            is, however, not uncommon to find long-range differences in the alloy           composition between different parts of the castings.  These are known           as macrosegregations, and they are serious defects which adversely              affect the physical and mechanical properties and workability.  Even            more deleterious are localized segregates, commonly referred to as              freckles or channel segregations, which are solute-rich, columnal               regions parallel to the direction of cooling in DS-processes.  The              objective of this research is to determine the mechanisms of fluid              mechanical origin by which freckles are formed in directionally                 solidified alloys.  Experiments and numerical investigations will be            carried out simultaneously to enhance the beneficial interactive                effect.
[{'FirstName': 'Chuan', 'LastName': 'Chen', 'PI_MID_INIT': 'F', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Chuan F Chen', 'EmailAddress': 'chen@ame.arizona.edu', 'NSF_ID': '000110144', 'StartDate': '06/15/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}, {'FirstName': 'David', 'LastName': 'Poirier', 'PI_MID_INIT': 'R', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'David R Poirier', 'EmailAddress': 'poirierd@u.arizona.edu', 'NSF_ID': '000108180', 'StartDate': '06/15/1987', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}]
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[{'Code': '144300', 'Text': 'FD-Fluid Dynamics'}, {'Code': '144600', 'Text': 'MATERIALS'}, {'Code': '912000', 'Text': 'CROSS-DIRECTORATE PROGRAMS'}]
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