Nanograin, Quasicrystalline, Multiphase Coatings for Reduced Friction an Wear

摘要

Recent progress in the development of quasicrystals (QCs) as low- friction, hard materials makes these alloys ideal candidates for protective coatings. However one disadvantage of quasicrystals is that they are quite brittle. To overcome this problem, we are taking advantage of nonstructural materials and produce coatings which consist of a nanograin quasicrystals and metal. Ultra smooth, nanograin Al-Cu-Fe-Cr and Al-Cu-Fe coatings with a nanohardness of 13 and 14 GPa respectively, were produced by Ion-beam assisted deposition (IBAD) and Pulsed laser Deposition (PLD) using targets prepared by the Materials Preparation Center at Ames Laboratory. Subsequent analysis by Ames Laboratory suggests that the coatings of Al-Cu-Fe-Cr produced are quasicrystalline in nature although an orthorhombic approximant cannot be ruled out by the data presented here. Ultra smooth, nanograin Al-Cu-Fe thin films produced where substantially depleted in Al and enriched in Fe relative to the composition region in which quasicrystals can be produced in this system. However, nanohardness and x-ray data suggest that our AlCuFe coatings may be consist of quasicrystals of AlCuFe and iron alloys. Clearly additional work in Phase II is necessary to determine the appropriate conditions for producing quasicrystalline thin films of Al-Cu-Fe using the production method used.