Grains can be extremely confusing, especially if you're an atom right on the boundary between two hot grains.
When a material is hot its component atoms thermally vibrate in place. As the temperature goes up there can be enough motion that grain boundaries blur and, whoops, the atom's on the other grain. This results in wholesale migration of atoms from one grain to another–especially from small grains to bigger ones. The subsequent grain growth explains how a powder can become a solid; little grains connect and fuse into bigger grains. Sintered materials explicitly start out as powder grains while "regular" metals develop grain by solidifying from molten material. The net result is that powders of most any material can become useful solids at relatively low temperatures. For a substance like tungsten this is handy because it melts at extremely high temperatures (3420°C) but can be made quite solid at 2300°C (a temperature just attained by the gases of a hot flame).
(gronkpan@vomitinglarry.bsky.social,
Sun 16 Nov 2008, 21:40,
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my cat's breath smells like cat food.
(baw__bagcontains traces of nuts on,
Sun 16 Nov 2008, 21:53,
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Eye eye..!!!
The sunday buffet at your house looks a treat as always..!! Excellent ....
(The invisable manIs having a long lazy soak in search,
Sun 16 Nov 2008, 21:46,
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