Synthesis of bulk nanostructured aluminum alloy ... - CiteSeerX
Acta Materialia 53 (2005) 5429–5438 www.actamat-journals.com
Synthesis of bulk nanostructured aluminum alloy component through vacuum plasma spray technique T. Laha a, A. Agarwal a
a,*
, T. McKechnie b, K. Rea c, S. Seal
c
Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, EC 3464, Miami, FL 33174, USA b Plasma Processes Inc., Huntsville, AL 35811, USA c Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA Received 3 July 2005; received in revised form 2 August 2005; accepted 11 August 2005 Available online 7 October 2005
Abstract The benefits of large-size engineering components with nanocrystalline structure (providing improved strength) are yet to be realized due to processing difficulties and associated grain growth problems. In this work, a free-standing bulk nanocrystalline structure of hypereutectic aluminum alloy (Al–21wt.%Si) has been fabricated through the vacuum plasma spray (VPS) forming technique using micron-size powder feedstock. Optical microscopy, scanning electron microscopy and transmission electron microscopy have been used to investigate the evolution of multi-scale microstructure as the result of rapid solidification in VPS forming process. The characterization implies the presence of nanosized eutectic Al–Si grains (25–100 nm) with uniformly distributed ultrafine primary silicon particles of submicron size. The effect of microstructural evolution on mechanical properties has been studied by tensile testing and microhardness measurement. A considerable improvement in ultimate tensile strength and hardness of the sprayed deposit has been observed in comparison with conventionally cast hypereutectic Al–17wt.%Si alloys. 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Aluminum alloys; Plasma spraying; Rapid solidification; Splat quenching; Nanostructured bulk component
1. Introduction Nanocrystalline materials, with typical grain sizes 75 lm) often remain unmelted or partially melted, which subsequently results in porosity and weak bonding in the spray deposited structure. On the other hand, finer particles (
Synthesis of bulk nanostructured aluminum alloy component through vacuum plasma spray technique T. Laha a, A. Agarwal a
a,*
, T. McKechnie b, K. Rea c, S. Seal
c
Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, EC 3464, Miami, FL 33174, USA b Plasma Processes Inc., Huntsville, AL 35811, USA c Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA Received 3 July 2005; received in revised form 2 August 2005; accepted 11 August 2005 Available online 7 October 2005
Abstract The benefits of large-size engineering components with nanocrystalline structure (providing improved strength) are yet to be realized due to processing difficulties and associated grain growth problems. In this work, a free-standing bulk nanocrystalline structure of hypereutectic aluminum alloy (Al–21wt.%Si) has been fabricated through the vacuum plasma spray (VPS) forming technique using micron-size powder feedstock. Optical microscopy, scanning electron microscopy and transmission electron microscopy have been used to investigate the evolution of multi-scale microstructure as the result of rapid solidification in VPS forming process. The characterization implies the presence of nanosized eutectic Al–Si grains (25–100 nm) with uniformly distributed ultrafine primary silicon particles of submicron size. The effect of microstructural evolution on mechanical properties has been studied by tensile testing and microhardness measurement. A considerable improvement in ultimate tensile strength and hardness of the sprayed deposit has been observed in comparison with conventionally cast hypereutectic Al–17wt.%Si alloys. 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Aluminum alloys; Plasma spraying; Rapid solidification; Splat quenching; Nanostructured bulk component
1. Introduction Nanocrystalline materials, with typical grain sizes 75 lm) often remain unmelted or partially melted, which subsequently results in porosity and weak bonding in the spray deposited structure. On the other hand, finer particles (
