Abstract
A NiTi shape memory alloy, known as nitinol, has been intensively studied for last five decades. The NiTi alloy with large size is commonly produced by vacuum sintering, thermal explosion mode of self-propagating high-temperature synthesis (TE-SHS) and spark plasma sintering (SPS). These methods are, however, rarely utilized for the forming of miniature and micro-sized components and have their own limits and disadvantages, such as long process chains and low efficiency with the processes. In the study reported in this paper, an innovation in rapid powder consolidation technology, called Micro-FAST (combining micro-forming and electric-current activated sintering techniques (FAST)) is introduced for the forming of micro-components in which the loose powders are loaded directly into the die, followed by electric-sintering. In the study, Φ4.0 mm × 4.0 mm miniature cylinders were formed with pre-alloyed NiTi powders. Sintered sample with relative density of 98.65% has been fabricated at a sintering temperature of 1150 °C in a relatively short cycle time (119.5 s). Based on the results of SEM and XRD, it was found that the densified samples with Ni3Ti, NiTi and NiTi2 phases were produced.
Highlights
Loose powders are placed directly into a small die, the heating is effected by passing an AC current through the die to generate the necessary temperature in the powders, and a pressure is applied onto the powders simultaneously
The morphology of a formed sample can be seen from Fig. 4
From the work completed in this study the following conclusions can be drawn: (1) Compared with conventional sintering methods, the Micro-FAST micro-manufacturing technology is an efficient process, and it has lower energy consumption and little impact to the environment due to directly forming the component from loose powders
Summary
Nickel-titanium alloy near the equiatomic concentration is well known for its shape memory effect (SME) [1], and its unique physical and mechanical properties, such as good ductility at room temperature, good vibration damping properties and corrosion properties in sea water [2]. The advantages of this technique over conventional ones include lower sintering temperature, shorter forming time, and marked improvements in sintering density. The pre-alloyed NiTi powders were rapidly consolidated by Micro-FAST to obtain miniature bulk samples
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
