Finite element analysis of severe plastic deformation of difficult-to-work material by equal-channel angular pressing at ambient temperature

An alternative technique of the equal-channel angular pressing (ECAP) process for difficult-to-work materials at ambient temperature is proposed by embedding a difficult-to-work material into an easy-to-work material. The easy-to-work material as a host material assists the deformation of the difficult-to-work material. The ECAP process is simulated by the finite element method (FEM). For this study, Ti as the difficult-to-work material is embedded into an Al-based functionally graded material (FGM) matrix. FEM is conducted with Ti embedded into a different host material type as well as a different die channel geometry. The strain distribution of the specimen after a single ECAP pass is analyzed. From the obtained results, it is found that the strain distribution in Ti is strongly influenced by the host material and the shape of the die channe

New Processing Routes for Functionally Graded Materials and Structures through Combinations of Powder Metallurgy and Casting

New processing routes for metal-matrix functionally graded materials (FGMs) and structures through combinations of powder metallurgy and casting are described in this chapter. Centrifugal mixed-powder method is introduced as a processing method for metal-matrix FGMs at first. The centrifugal mixed-powder method is a developed technique of centrifugal casting by setting predesigned mixed powder in a spinning mold in advance. As an example of processed FGMs by this method in our previous studies, Cu-based FGMs with dispersed diamond particles are shown. Graded structures in the Cu-based FGMs are investigated through scanning electron microscope (SEM) observations of microstructures. As the latest processing method for metal-matrix FGMs developed by our research group, centrifugal sintered-casting method is shown. The centrifugal sintered-casting method is a modified processing technique of the centrifugal mixed-powder method. In the centrifugal sintered-casting method, FGMs are processed by the combination of centrifugal sintering and centrifugal casting. Al–Si alloy and Cu-based FGMs with dispersed diamond particles are introduced as examples. Applications of metal-matrix FGMs processed by the centrifugal sintered-casting method are also described. Fabricated metal-matrix FGMs can be used as grinding wheel and applied to carbon fiber-reinforced plastic (CFRP) machining

Fabrication of Al-Al3Ti/Ti3Al Functionally Graded Materials under a Centrifugal Force

material

Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys

We found that specific biomedical Ti and its alloys, such as CP Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O, form a bright white oxide layer after a particular oxidation heat treatment. In this paper, the interfacial microstructure of the oxide layer on Ti–29Nb–13Ta–4.6Zr and the exfoliation resistance of commercially pure (CP) Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O were investigated. The alloys investigated were oxidized at 1273 or 1323 K for 0.3–3.6 ks in an air furnace. The exfoliation stress of the oxide layer was high in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, and the maximum exfoliation stress was as high as 70 MPa, which is almost the same as the stress exhibited by epoxy adhesives, whereas the exfoliation stress of the oxide layer on CP Ti was less than 7 MPa, regardless of duration time. The nanoindentation hardness and frictional coefficients of the oxide layer on Ti–29Nb–13Ta–4.6Zr suggested that the oxide layer was hard and robust enough for artificial tooth coating. The cross-sectional transmission electron microscopic observations of the microstructure of oxidized Ti–29Nb–13Ta–4.6Zr revealed that a continuous oxide layer formed on the surface of the alloys. The Au marker method revealed that both in- and out-diffusion occur during oxidation in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, whereas only out-diffusion governs oxidation in CP Ti. The obtained results indicate that the high exfoliation resistance of the oxide layer on Ti–29Nb–13Ta–4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O are attributed to their dense microstructures composing of fine particles, and a composition-graded interfacial microstructure. On the basis of the results of our microstructural observations, the oxide formation mechanism of the Ti–Nb–Ta–Zr alloy is discussed

White-Ceramic Conversion on Ti-29Nb-13Ta-4.6Zr Surface for Dental Applications

Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has excellent mechanical properties and bone conductivity. For dental application, TNTZ surfaces were converted to white oxidized layer by a simple heat treatment in air to achieve the formation of aesthetic surfaces. The oxidized layer formed by the heat treatment at 1000°C for 0.5 or 1 hr was whiter and joined to TNTZ substrate more strongly than that formed by the treatment at 900°C. The layer consisted of TiO2 (rutile), TiNb2O7, and TiTa2O7 and possessed ~30 μm in thickness for the sample heat-treated at 1000°C and ~10 μm for that heat-treated at 900°C. The surface average roughness and the wettability increased after the heat treatment. The spreading and proliferation level of mouse osteoblast-like cell (MC3T3-E1 cell) on the heat-treated sample were almost the same as those on as-prepared one. The cell spreading on TNTZ was better than those on pure titanium (CP Ti) regardless of the heat treatment for the samples. There was no deterioration in the in vitro cell compatibility of TNTZ after the oxidized layer coating by the heat treatment