Manufacturing of Porous Al-Cr Preforms for Composite Reinforcing Using Microwave Activated Combustion Synthesis

• Main Authors: Naplocha K., Granat K.
• Format: Article
• Language: English
• Published: Polish Academy of Sciences 2014-10-01
• Series: Archives of Metallurgy and Materials
• Subjects: SHS; microwave; Al-Cr; preform; composite
• Online Access: http://www.degruyter.com/view/j/amm.2014.59.issue-3/amm-2014-0196/amm-2014-0196.xml?format=INT

The combustion synthesis of porous skeletons (preforms) of intermetallic Al–Cr compounds intended for metal matrix composite MMC reinforcing was developed. Mixture of Al and Cr powders with granularity of −10, −44, −74mm were cold isostatic pressed and next ignited and synthetized in a microwave reactor under argon atmosphere (microwave-activated combustion synthesis MACS). In order to ignite the synthesis, microwave energy was focused by a tuner on the specimen. The analysis of reaction temperature diagrams revealed that the synthesis proceeded through the following peritectic transformations: L(liquidus)+Al7Cr→L+Al11Cr2→L+Al4Cr. Moreover, EDS and XRD examinations showed that the reaction proceeded between a solid Cr and a liquid Al to create a distinct envelope of Al9Cr4 on Cr particle which next extended and spreaded over the entire structure. The produced preforms with uniform structure and interconnected porosity were infiltrated with liquid Cu and Al alloy. The obtained composite materials exhibited high hardness, wear and distinct temperature oxidation resistance.