Download or read book Processing, Microstructure and Mechanical Behavior of Cryomilled Commercially Pure Titanium written by Osman Ertorer and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cryomilling has been proposed as an effective technique for large-scale production of nanostructured (NS) and ultra-fine-grained (UFG) metals, which attract significant interest due to their unique physical properties and potential applications. Cryomilling technique was successfully utilized for synthesis of NS and UFG Al, and Ni alloys with enhanced mechanical properties as reported in other relevant studies. However, the technique itself and subsequent consolidations were found to result in large variations in terms of chemistry, microstructure and properties, in relation with the process parameters and particular material chemistries. In this sense, the present dissertation research was motivated by the lack of fundamental understanding of the structure and behavior of cryomilled materials, particularly as applied to hcp systems such as Ti. Accordingly, in this study, NS commercially pure (CP) Ti powders were synthesized using the cryomilling technique utilizing variety of processing parameters. Characterization of microstructures showed that powders with average grain sizes of ~20 nm can be synthesized after 8 hours of cryomilling in liquid Ar or liquid N2 medium. A significant increase in concentrations of interstitial solute atoms (i.e., N, O, and C) was also detected as a result of cryomilling. Quasi-isostatic (QI) forging or spark plasma sintering (SPS) techniques were used for consolidation of powders. The consolidated bulk samples were found to accommodate larger grains (i.e., 50 nm to several microns) as a result of grain growth. Room temperature tensile testing results showed that, some of the bulk cryomilled samples exhibit enhanced tensile strength (YS ~ 800-900 MPa) without significant loss in ductility (~30% elongation at failure), as compared to that of their coarse-grained conventional counter parts. The mechanical behavior is rationalized on the basis of processing history, microstructure, and chemistry. The enhanced strength is attributed to grain boundary strengthening as a result of refined microstructure and solid solution strengthening as result of increased interstitial solute content. The retained ductility is attributed to presence of a multi-modal structure, balanced interstitial solute content and high strain rate sensitivity.