MONITORING OF MELTING AND SOLID-STATE PHASE-TRANSFORMATION INDUCED BYPULSED-LASER ACTION ON PURE ZIRCONIUM

Real time temperature monitoring is carried out by high speed high spa tial resolution pyrometers. The obtained thermocycles are compared wit h a 2D transient heat transfer model, which permits calculation of the evolution (depth, volume, shape, etc.) of the molten pool as well as the solid state (beta --> alpha) phase transformation induced by the p ulsed laser action. As a result, the correlation between surface tempe rature dynamics measured by pyrometer and parameters of phase transfor mations are studied. A phenomenological relation between molten pool e volution (obtained by simulation) and duration of solidification (meas ured by pyrometer) is presented for different values of the density en ergy flux.