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There are a total of 23 record(s) matching your query.
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Planetary materials and resource utilization: An interdisciplinary engineering design course at Michigan Technological University
Author(s): Rose, W. I.; Paces, J. B.; Chesner, C. A.; Pletka, B. J.; Hellawell, A.; Kawatra, S. K.; Pilling, J. E.
Abstract: A new course was developed and instituted in the spring quarter of 1989 dealing with topics related to space resource utilization and related engineering. The course development required a concerted, coordinated effort, ...
NASA Center: NASA (non Center Specific)
Publication Year: 1990
Added to NTRS: 2008-05-31
Accession Number: 91N22180; Document ID: 19910012867
Directional Solidification of Monotectic Alloys
Author(s): Hellawell, A.
Abstract: Cooling at certain rates produced fibrous composite structures. Alloy samples melted in alumina or graphite crucibles under argon and then chillcast into 33-mm-diameter rods or sucked directly into 3-mm-bore alumina or ...
NASA Center: Marshall Space Flight Center
Publication Year: 1983
Added to NTRS: 2005-09-30
Accession Number: 83B10159; Document ID: 19830000159; Report Number: MFS-25767
Grain Evolution in Conventional and Rheo-Castings
Author(s): Hellawell, A.
Abstract: Nucleation and growth in a conventional, unstirred casting are briefly reviewed and then compared with the probable situation in rheo-cast samples. Emphasis is placed on factors which determine the final grain size within a ...
NASA Center: Glenn Research Center
Publication Year: 1996
Added to NTRS: 2005-08-25
Accession Number: 97N26612; Document ID: 19970027695; Report Number: NAS 1.26:205375, NASA-CR-205375
Channel flow in partly solidified alloy systems
Author(s): Sarazin, J. R.; Hellawell, A.
Abstract: No Abstract Available
NASA Center: NASA (non Center Specific)
Publication Year: 1988
Added to NTRS: 2005-08-25
Accession Number: 89N70418; Document ID: 19890068045; Report Number: NAS 1.26:184888, NASA-CR-184888
Channel Segregation in Alloy Ingots
Author(s): Hellawell, A.
Abstract: General patterns of fluid flow are considered for various geometrical arrangements with interdendritic liquid either less or more dense than bulk liquid. The incidence of channel formation is described and mechanisms ...
NASA Center: Glenn Research Center
Publication Year: 1985
Added to NTRS: 2005-08-25
Accession Number: 97N72124; Document ID: 19970022501; Report Number: NAS 1.26:203795, NASA-CR-203795
Some Consequences of Thermosolutal Convection: The Grain Structure of Castings
Author(s): Hansen, G.; Hellawell, A.; Lu, S. Z.; Steube, R. S.
Abstract: The essential principles of thermosolutal convection are outlined, and how convection provides a transport mechanism between the mushy region of a casting and the open bulk liquid is illustrated. The convective flow patterns ...
NASA Center: Glenn Research Center
Publication Year: 1996
Added to NTRS: 2005-08-25
Accession Number: 97N26088; Document ID: 19970026972; Report Number: NAS 1.26:205241, NASA-CR-205241
The Grain Structure of Castings: Some Aspects of Modelling
Author(s): Hellawell, A.
Abstract: The efficacy of the modelling of the solidification of castings is typically tested against observed cooling curves and the final grain structures and sizes. Without thermo solutal convection, equiaxed grain formation is ...
NASA Center: Glenn Research Center
Publication Year: 1995
Added to NTRS: 2005-08-25
Accession Number: 97N27319; Document ID: 19970028573; Report Number: NAS 1.26:205384, NASA-CR-205384
Micro- and Macro-Segregation During Alloy Solidification
Author(s): Hellawell, A.
Abstract: To attempt a comprehensive review of this subject area, with all the ramifications and consequences associated with grain size and distribution is beyond the scope of this presentation. Therefore, to be more selective, there ...
NASA Center: Glenn Research Center
Publication Year: 1990
Added to NTRS: 2005-08-25
Accession Number: 97N72202; Document ID: 19970023622; Report Number: NAS 1.26:203796, NASA-CR-203796
Primary Particle Melting Rates and Equiaxed Grain Nucleation
Author(s): Han, Q.; Hellawell, A.
Abstract: This article is concerned with the survival of a relatively dilute dispersion of small solid particles (e.g, 20 micrometers) in a large bath of liquid, at temperatures above the liquidus temperature of some alloy system. The ...
NASA Center: Glenn Research Center
Publication Year: 1997
Added to NTRS: 2005-08-25
Accession Number: 97N30700; Document ID: 19970036385; Report Number: NAS 1.26:205240, NASA-CR-205240
Communications: Mechanical Deformation of Dendrites by Fluid Flow
Author(s): Pilling, J.; Hellawell, A.
Abstract: It is generally accepted that liquid agitation during alloy solidification assists in crystal multiplication, as in dendrite fragmentation and the detachment of side arms in the mushy region of a casting. Even without ...
NASA Center: Glenn Research Center
Publication Year: 1996
Added to NTRS: 2005-08-25
Document ID: 19980007072; Report Number: NAS 1.26:205239, NASA-CR-205239
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