Mechanical Properties of High Strength Aluminum Alloys Formed by Pulsed Laser Deposition

Abstract

ABSTRACTVery high-strength alloys of Al(O) have been formed using a pulsed laser deposition (PLD) system to deposit from alternating targets of Al and Al2O3. Ion beam analysis and transmission electron microscopy show that the deposited material is uniform in composition with up to 33 at.% O and has a highly refined microstructure consisting of a fine, uniform dispersion of ∼1 nm diameter γ-Al2O3 precipitates. Ultra-low-load indentation testing combined with finite-element modeling is used to determine the mechanical properties of the layers. Yield stresses as high as 5.1 GPa have been measured in these materials, greatly exceeding the strengths of aerospace Al alloys (∼0.5 GPa) and even high strength steels. The key to the properties of these materials is the dispersion of small, hard precipitates spaced only a few Burgers vectors apart; dislocations are apparently unable to cut through and must bow around them.