Microscale energy transfer during picosecond laser melting of metal films

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:428098

Kuo, L S; Qiu, T ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Mechanical Engineering

Laser melting of metal films involves microscopic energy transfer processes: absorption of photon energy by free electrons, energy exchange between electrons and the lattice, and initiation of phase change of the lattice. During picosecond (10{sup {minus}12}s) laser heating, electrons and the lattice are not in thermal equilibrium. On the other hand, rapid laser heating produces a large degree of superheating and undercooling during melting and solidification. This work developed a general model to characterize both the nonequilibrium electron-lattice heating process and the nonequilibrium phase-change process for ultrashort-laser-pulse melting of metal films. The results show that the nonequilibrium heating process significantly increases the laser melting threshold, enlarges the thermal-affected region, reduces the lattice temperature rise, prolongs the melting duration, and reduces the solidification speed. These results are important for material processing with ultrashort laser pulses.

• OSTI ID: 428098
• Report Number(s): CONF-960815--; ISBN 0-7918-1505-6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
GOLD
LASER RADIATION
MATHEMATICAL MODELS
MELTING
NUMERICAL ANALYSIS
THEORETICAL DATA