A Laser Heating Device for Metallographic Studies Available to Purchase

Using an optically pumped ruby laser for a heat source and a helium-water vapor quench, thin metallic specimens can be heated at a rate of 10⁶ C/sec and cooled at a rate of 10⁵ C/sec. An electronic timing circuit controls time spent at a temperature so that heating times as short as 0.001 sec are possible. The temperature reached is determined by the energy of the laser pulse, specimen reflectivity, and thickness. Oxidation of iron surface effectively reduces reflection and, thus, increases energy absorption. Temperature distribution across sections of the specimens is a function of density and thermal diffusivity. For an 0.002-in. iron specimen, front and back temperatures remain nearly equal during heating. Applications of the technique included in this paper are: studies of recrystallization and phase transformation of pure iron, dissolution of pearlite and spheroidite in a eutectoid iron-carbon alloy, and melting and solidification of gold.