Macroscopic Surface Structures formed on Boron upon Solidification

Abstract

THE purpose of this communication is to report some interesting surface structures that formed on a boron surface upon solidification from the melt. Melting was accomplished by electrical resistance heating of rods of polycrystalline boron about 1 mm. in diameter and several centimetres in length in a helium atmosphere. The current through the rod was slowly increased until it melted at the midpoint at about 2,000° C. and separated into two pieces, at which time heating ceased and the melted boron, held on the tips of the remaining pieces, solidified and cooled below red heat within a few seconds.