Abstract: A cylindrically hollow segmented thermal gradient furnace enclosing metal or semiconductor material wherein each segment includes a heater for raising the temperature of the metal. The material is encircled by a heat pipe which is coupled to a heat exchanger for rapidly cooling a corresponding segment of the material after the heater has performed a thermal soak of the material. A reservoir is filled with inert gas which is selectively expanded to block cooling at the heat exchanger when the heater is turned on and compressed to allow cooling at the exchanger when the heater is turned off so that a sharp thermal gradient may be established along the length of the material.