Laser production of ultra-fine particles of alloys and metal-ceramic mixtures

Abstract

The production of ultra-fine particles of alloys and metal-nitride mixtures was attempted by the pulsed Nd:YAG laser heating-evaporation of various Ni-Ti, Fe-Ti or Cu-Ni target alloys or partly Fe-Ti-powder mixtures in Argon or Nitrogen atmosphere. Especially, characteristics of particle morphology and size distribution, and compositions and lattice structures of alloy particles or the metal:nitride ratio of mixture particles were examined and compared with the properties of target materials. As a result, ultra-fine alloy particles of less than 150 nm in maximum size could be produced in spherical or polyhedral shape from their target alloys or powder mixtures in Ar atmosphere at 0.1 MPa (1 atm). The chemical compositions and structures were generally different from those of target materials, and the reason was interpreted in terms of the fact that the volatile element was enriched in the evaporated particles. Moreover, in N2 atmosphere, ultra-fine particles of metal-nitride mixtures such as Ni and TiN or Fe and TiN were formed from Ni-Ti or Fe-Ti alloys, respectively. The mixture ratio appeared controllable by selecting alloy compositions.The production of ultra-fine particles of alloys and metal-nitride mixtures was attempted by the pulsed Nd:YAG laser heating-evaporation of various Ni-Ti, Fe-Ti or Cu-Ni target alloys or partly Fe-Ti-powder mixtures in Argon or Nitrogen atmosphere. Especially, characteristics of particle morphology and size distribution, and compositions and lattice structures of alloy particles or the metal:nitride ratio of mixture particles were examined and compared with the properties of target materials. As a result, ultra-fine alloy particles of less than 150 nm in maximum size could be produced in spherical or polyhedral shape from their target alloys or powder mixtures in Ar atmosphere at 0.1 MPa (1 atm). The chemical compositions and structures were generally different from those of target materials, and the reason was interpreted in terms of the fact that the volatile element was enriched in the evaporated particles. Moreover, in N2 atmosphere, ultra-fine particles of metal-nitride mixtures such as Ni and TiN or...