The effect of minor additions of titanium on the fracture toughness of Fe-12 at% Ni alloys at?196� C

Titanium Powders via Gas-Solid Direct Reaction Process and Mechanical Properties of Their Extruded Materials

“…In general, the interstitial solid solution of hetero-atoms like nitrogen and oxygen in ¡-Ti caused the expansion of c-axis while a-axis was much less affected by them. 5,12) However, almost no changes in not only a-axis but also c-axis, suggesting no solid solution of nitrogen atoms in the N-treated powders, were observed in Fig. 6, which is consistent with the results of microstructural analysis on the N-treated powders described in Fig.…”

“…This phenomenon could be explained by Ti-N phase diagram 22) based on the total nitrogen content of the wrought Ti-N materials (as low as 2.98 at% in N180), which was significantly low level compared with the maximum solubility of approximately 20 at% at consolidation temperature of 1273 K. Therefore, the interstitial solid solutions of additive nitrogen atoms are expected to enhance the mechanical strength of the wrought Ti-N materials. 5,6,12) In addition, the similar peak intensity ratio obtained from the XRD profiles suggests that the crystallographic texture of the Ti matrix was not significantly influenced by nitrogen addition in the range of this study.…”

“…In the present study, instead of the conventional rare earth alloying elements, nitrogen, one of the ULEs, was employed as an interstitial solid solution strengthening element for Ti to achieve the novel Ti materials with outstanding mechanical properties. Nitrogen can dissolve in ¡-Ti to form an interstitial solid solution in large amounts of approximately 20 at%, 5) which showed a dramatically high hardness response and tensile strengthening in the Ti matrix. 5,6) The Ti powders with various nitrogen contents were prepared by a gas (N 2 )-solid (Ti starting powder) direct reaction process.…”

“…Nitrogen can dissolve in ¡-Ti to form an interstitial solid solution in large amounts of approximately 20 at%, 5) which showed a dramatically high hardness response and tensile strengthening in the Ti matrix. 5,6) The Ti powders with various nitrogen contents were prepared by a gas (N 2 )-solid (Ti starting powder) direct reaction process. In order to consolidate the Ti powders containing additive nitrogen, a spark plasma sintering (SPS) technique and subsequent hot extrusion were performed to fabricate extruded powder metallurgy (P/M) Ti-N materials.…”