Crystal growth of vanadium by arc-zone melting

This paper reports on crystal growth by the arc-zone melting technique that has been used over the past 25 years to prepare single crystals of the refractory metals and their alloys. During arc-zone melting only the upper surface of the metal is melted yet the entire cross section of the rod becomes single crystalline. A process parameter study was conducted to determine the operating mechanisms of crystal growth. Crystal growth occurs in the solid state and is a result of large scale grain boundary migration. A minimum power input to the arc is required to prepare crystals and this was related to minimum temperature necessary for boundary migration. A series of quenching experiments indicates that boundary migration is driven by abnormal grain growth processes. One unique advantage of this technique over conventional crystal growth methods is in the preparation of alloys containing a volatile component such as Al, Cr or Mn. Loss of the high vapor pressure component during arc-zone melting is restricted only to the molten region and a crystal of the desired composition can be sectioned from the lower portion of the finger