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Title: Reactive spark plasma sintering (SPS) of nitride reinforced titanium alloy composites

Coupled in situ alloying and nitridation of titanium–vanadium alloys, has been achieved by introducing reactive nitrogen gas during the spark plasma sintering (SPS) of blended titanium and vanadium elemental powders, leading to a new class of nitride reinforced titanium alloy composites. The resulting microstructure includes precipitates of the d-TiN phase with the NaCl structure, equiaxed (or globular) precipitates of a nitrogen enriched hcp a(Ti,N) phase with a c/a ratio more than what is expected for pure hcp Ti, and fine scale plate-shaped precipitates of hcp a-Ti, distributed within a bcc b matrix. During SPS processing, the d-TiN phase appears to form at a temperature of 1400 C, while only hcp a(Ti,N) and a-Ti phases form at lower processing temperatures. Consequently, the highest microhardness is exhibited by the composite processed at 1400 C while those processed at 1300 C or below exhibit lower values. Processing at temperatures below 1300 C, resulted in an incomplete alloying of the blend of titanium and vanadium powders. These d-TiN precipitates act as heterogeneous nucleation sites for the a(Ti,N) precipitates that appear to engulf and exhibit an orientation relationship with the nitride phase at the center. Furthermore, fine scale a-Ti plates are precipitated within the nitridemore » precipitates, presumably resulting from the retrograde solubility of nitrogen in titanium.« less
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Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Alloys and Compounds; Journal Volume: 617
Research Org:
Argonne National Laboratory (ANL)
Sponsoring Org:
USDOE Office of Science - Office of Basic Energy Sciences; Air Force Research Laboratory
Country of Publication:
United States
Sintering; metal-matrix composites; microstructure; synchrotron radiation; transmission electron microscopy