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Erdman, Robert G.

Publications and source records attributed to Erdman, Robert G..

2 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Controlled Directional Solidification of Aluminum - 7 wt Percent Silicon Alloys: Comparison Between Samples Processed on Earth and in the Microgravity Environment Aboard the International Space Station

An overview of the international "MIcrostructure Formation in CASTing of Technical Alloys" (MICAST) program is given. Directional solidification processing of metals and alloys is described, and why experiments conducted in the microgravity environment aboard the International Space Station (ISS) are expected to promote our understanding of this commercially relevant practice. Microstructural differences observed when comparing the aluminum - 7 wt% silicon alloys directionally solidified on Earth to those aboard the ISS are presented and discussed.

Grugel, Richard N.↗
NASA NTRS2012

Primary Dendrite Array: Observations from Ground-Based and Space Station Processed Samples

Influence of natural convection on primary dendrite array morphology during directional solidification is being investigated under a collaborative European Space Agency-NASA joint research program, Microstructure Formation in Castings of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST). Two Aluminum-7 wt pct Silicon alloy samples, MICAST6 and MICAST7, were directionally solidified in microgravity on the International Space Station. Terrestrially grown dendritic monocrystal cylindrical samples were remelted and directionally solidified at 18 K per centimeter (MICAST6) and 28 K per centimeter (MICAST7). Directional solidification involved a growth speed step increase (MICAST6-from 5 to 50 millimeters per second) and a speed decrease (MICAST7-from 20 to 10 millimeters per second). Distribution and morphology of primary dendrites is currently being characterized in these samples, and also in samples solidified on earth under nominally similar thermal gradients and growth speeds. Primary dendrite spacing and trunk diameter measurements from this investigation will be presented.

Tewari, Surendra N.↗