Metastable Phases Produced In Nickel By High Dose La And 0 Implantation, And Pulsed Laser Melt Quenching

Abstract

ABSTRACTNickel single crystals implanted with La, 0 and La + 0, up to about 9 a/o concentrations were irradiated with spatially homogenised ruby laser pulses (16 ns FWHM) up to 3.7 J/cm2 in vacuum (s~ 10−2 Torr). Phase changes, defect structure and solute migration were studied before and after laser melt quenching using RBS/channeling, TEM and SEM techniques.Both La and La + 0 implants produced a buried amorphous layer on top of a polycrystalline layer above the single crystal matrix. 0 implants did not produce an amorphous phase, but a buried layer containing polycrystalline Ni, metastable hcp Ni particles and a dense dislocation network was formed. Pulsed laser melt quenching of these implanted metastable phases lead to a variety of new phases - all crystalline.