Again this is mentioned previously in a well buried post on the old BBS. Thank goodness this place has forums so that such things might not get buried in the future. (provided we post to the correct forum,intelligently)
Once a grid is formed and the fusor operated, the wire CONFORMS and eventually hydrogen embrittlement will set in. This is a wonderful thing indeed. Wire which at first was springy and seeking to pop apart and open up, is now rigid in space forever. Frozen forever like a dried out cookie.
This came to the fore when I would silver solder my early grids. I became concerned that as the grids glowed red orange and moved on to white heat, the silver soldered wires might pop open. None ever did. The reason was H2 embrittlement. Nothing ever came apart due to the high surface tension of the liquified silver alloy. It was an un-appreciated benifit. Inspection of older grids confirmed this fact. They crumble like a potato chip or break like glass if stressed. A small piece can be broken out of a grid loop and the rest just stays in place. (note that this is for Ta and W wires only. I left stainless steel grids behind long ago with fusor I.
Richard Hull
Created on Thursday, February 15, 2001 1:41 PM EDT by Richard Hull