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Microstructural investigation of hard phases in as-cast Ni-Ti memory alloy

Badakhshan Raz, S ; Sharif University of Technology | 2005

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  1. Type of Document: Article
  2. DOI: 10.3139/147.100277
  3. Publisher: Carl Hanser Verlag , 2005
  4. Abstract:
  5. Ti4Ni2O, Ti4Ni2N, TiC and Ti2Ni are brittle compounds usually formed during production and processing of the Ti-Ni SMA alloys. These compounds adversely affect on workability and shape memory properties of the alloy. This paper presents most recent findings related to the morphologies of various inclusions and Ti-Ni phases formed during and after vacuum induction melting and casting of Ti-45wt.% Ni material. Cast samples were mechanically and/or electrolytically polished and etched. Extensive optical and scanning electron microscopic studies were carried out to characterize the composition and microstructure of the as cast Ti-Ni alloys. Results indicated that mechanical polishing followed by etching was not proficient to reveal sufficient data on physical specifications and morphological changes of the born brittle oxide and nitride and carbide phases. An innovative set of electropolishing/etching conditions was, therefore, prescribed to yield detailed information on morphologies of the brittle phases. Experimental conditions were devised for characterization of the Ti 2Ni precipitates, as well. © Carl Hanser Verlag, München
  6. Keywords:
  7. Brittleness ; Electrolytic polishing ; Electron microscopes ; Microstructure ; Shape memory effect ; Titanium compounds ; Vacuum applications ; Brittle oxides ; Carbide phases ; Mechanical polishing ; Shape memory properties ; Nickel alloys
  8. Source: Praktische Metallographie/Practical Metallography ; Volume 42, Issue 9 , 2005 , Pages 454-469 ; 0032678X (ISSN)
  9. URL: https://www.degruyter.com/document/doi/10.3139/147.100277/html