Rheological Investigation of Prealloyed NiTi Shape Memory Alloy Powders

Abstract

Usage areas of Nickel-Titanium shape memory alloys (SMA) have become widespread gradually and new production techniques on these alloys have been improved nowadays. Especially its unique shape memory effect (SME) and employability in many areas have a crucial role in making it widespread. In experimental works, rheological studies have been done for powder injection molding by using prealloyed NiTi powders which are 10 µm, 14 µm and 30 µm sizes. In this study, SEM, EDS, TG, DTA and DSC analyses have been used to determine rheological properties, transformation temperatures and appropriate binder system. Polypropylene, polyethylene glycol 8000 and stearic acid have been used for appropriate prescription system in the work. To determine the optimum production conditions with obtained prescription, different powder-binder rates (60-70 wt% powder) between 160˚-200˚ temperature ranges have been tried. Since PEG series binder has been used in production of parts, two stage debiding process has been carried out. The best molding quantifications have been determined with powders which are 10 µm and 14 µm sizes and 62-64% powder loading rates.