Hirobumi Tobe
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View article: Shape memory alloys for cryogenic actuators
Shape memory alloys for cryogenic actuators Open
Actuators are widely used in various mechanical products. However, there have been no actuators that can exhibit high actuation stresses and strains at cryogenic temperatures. Although shape memory alloys (SMAs) are attractive candidates f…
View article: Strength enhancement strategies in brazing Ti alloys to non‐oxide ceramics: An overview of Ti–6Al–4V/Si <sub>3</sub> N <sub>4</sub> joints
Strength enhancement strategies in brazing Ti alloys to non‐oxide ceramics: An overview of Ti–6Al–4V/Si <sub>3</sub> N <sub>4</sub> joints Open
The growing demand for lightweight, heat‐resistant aerospace structures with intricate geometries has driven the integration of non‐oxide ceramics and Ti alloys, addressing the inherent workability and scalability challenges associated wit…
View article: Effect of Nb interlayer on residual and bending stress relaxation in Si<sub>3</sub>N<sub>4</sub>/Nb/Ti-6Al-4V joints
Effect of Nb interlayer on residual and bending stress relaxation in Si<sub>3</sub>N<sub>4</sub>/Nb/Ti-6Al-4V joints Open
In dissimilar joints between Si3N4 and Ti-6Al-4V, insertion of a ductile Nb interlayer is effective for stress relaxation under bonding and loading. In this study, elastoplastic analysis using the finite element method (FEM) was applied to…
View article: Novel Ti–20Zr–49.7Pd High Temperature Shape Memory Alloy with Facilitated Detwinning and Precipitation Strengthening
Novel Ti–20Zr–49.7Pd High Temperature Shape Memory Alloy with Facilitated Detwinning and Precipitation Strengthening Open
It is desirable to develop high temperature shape memory alloys (HTSMAs) with a martensitic transformation start temperature (Ms) above 100°C and a recoverable strain of about 4–6% in the shape memory effect. The latter property is achieve…
View article: Deployable Rocket Nozzle Utilizing Superelastic Titanium Alloy Sheet
Deployable Rocket Nozzle Utilizing Superelastic Titanium Alloy Sheet Open
A novel deployable rocket nozzle utilizing superelasticity was proposed in this study. Ti–4.5Al–3V–2Fe–2Mo alloy (SP-700) sheets were heat-treated to have appropriate α/β ratio so that the sheet shows superelasticity at room temperature. A…
View article: Evaluation of the Strength of Brazed Joints in Ceramics/Metal Thruster
Evaluation of the Strength of Brazed Joints in Ceramics/Metal Thruster Open
Ceramic/metal brazing was investigated to produce light-weight and highly-efficient ceramic thrusters. Silicon nitride ceramic and metal bars were brazed using an Ag-based brazing material. Four-point bend tests were conducted at room and …
View article: Preliminary System Design of Small Lunar Landing Demonstrator SLIM
Preliminary System Design of Small Lunar Landing Demonstrator SLIM Open
SLIM (Smart Lander for Investigating Moon) is the Lunar Landing Demonstrator which is under development at ISAS/JAXA. SLIM demonstrates not only so-called Pin-Point Landing Technique to the lunar surface, but also demonstrates the design t…
View article: Low-temperature creep mechanism in ultrafine-grained aluminum
Low-temperature creep mechanism in ultrafine-grained aluminum Open
This study investigated the low-temperature creep mechanisms in ultra-fine grained aluminum made by accumulative roll bonding. The low-temperature creep behaviors in ultra-fine grained aluminum with grain size of 0.39 µm were divided into …
View article: Initial process of continuous dynamic recrystallization in a superplastic Al–Mg–Mn alloy
Initial process of continuous dynamic recrystallization in a superplastic Al–Mg–Mn alloy Open
Microstructural evolution during region III deformation (T=723 K, ε̇=10−1 s−1) in a superplastic Al–Mg–Mn alloy (ALNOVI-U) was investigated. Surface makers drawn by focused ion beams (FIB) and internal observation by the electron back-scatt…
View article: Effect of heat-treatment temperature on shape memory properties of Ti–4.5Al–3V–2Fe–2Mo alloy
Effect of heat-treatment temperature on shape memory properties of Ti–4.5Al–3V–2Fe–2Mo alloy Open
In this study, effects of heat-treatment temperature on microstructure, lattice parameters of martensite phase, and shape memory properties of Ti–4.5Al–3V–2Fe–2Mo alloy (SP-700) were investigated. The volume fraction of α phase decreased a…