Laser-beam and photon-assisted processed materials and their microstructures

Laser processing is a relatively new technique for modifying the near-surface region of materials without altering the in-bulk characteristics. A single laser can perform several functions by manipulating processing conditions such as laser power, beam diameter, and traverse speed. Lasers have shown attractive applications, such as cutting, welding, glazing, alloying, and cladding. A laser glazing process has demonstrated an improvement in the microstructure of vacuum plasma-coated copper-based alloys containing cavities, unmelted particles, and segregation. Laser glazing has also been shown to restore the degraded microstructure of components and make them equivalent to, or better than, the original wrought alloy. The laser cladding concept was used to develop nickel-based alloys for high-temperature applications that exhibited higher thermal stability than the nickel-based Rene-95 alloy. Rapid melting and quenching occurred during the laser glazing, alloying, and cladding processes resulting in a fine-grained microstructure, metastable phases and extended solid solubility of alloying additions in the matrix. Photon-assisted processing of material is a relatively new technique being explored to synthesize new materials from various substrates (solid, liquid, and gas). This process is successfully used to fabricate high-quality thin films for electronic industries. Thin films of multicomponents can be deposited with stoichiometric composition. Diamond thin films have been synthesized from liquid hydrocarbon (Benzene, C₆H₆) by laser-liquid hydrocarbon-substrate interaction. A laser-assisted physical vapour deposition process was found to be very successful in depositing stoichiometric compositions of multilayered thin films such as superconducting YBa₂Cu₃O₇, ferroelectric Pb_0.52Zr_0.48TiO₃ and other coatings such as TiN and CoSi₂. This review reports some of the major advances in the understanding and engineering of new materials for electronic industries and high-temperature applications in the auto, aerospace, and turbine industries.