Effects of current intensity and cumulative exposure time on the localized current-activated sintering of titanium nickelides
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This article discusses the processing and properties of titanium nickelides locally sintered via Current-Activated Tip-based Sintering (CATS), a new localized sintering process. One of the advantages of CATS is the ability to apply orders of magnitude higher current densities than conventionally possible, which can promote rapid sintering and phase transformation rates. Mechanically alloyed equi-atomic Ni–Ti powder was for the first time tip sintered at varying current intensities and cumulative current exposure time. The effect of current-control processing conditions on the evolution of the locally sintered Ni–Ti microstructure and properties are discussed. The size of the locally sintered process zone was found to increase with cumulative current exposure time. The degree of sintering, phase transformations, and properties were found to depend on the current intensity, cumulative current exposure time and distance away from the tip/compact interface. Fully/near fully dense material was achieved rapidly at locations exposed to the highest current densities.
KeywordsMechanical Alloy Spark Plasma Sinter Process Zone Ni3Ti Titanium Nickelides
The authors express their thanks to Dr. Steve Barlow and Ms. Joan Kimbrough for their help with electron microscopy and XRD. Thanks are also to Mr. Greg Morris and Mr. Mike Lester for general technical support. The authors also wish to thank The National Science Foundation (CMMI division: grant no. 0826532) for their support.
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