Related Experiment Video
Updated: Jun 18, 2026
11:54
Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures
Published on: February 8, 2018
10.3K
Phase Equilibria, Solidified Microstructure, and Hydrogen Transport Behaviour in the V-Ti-Co System
Erhu Yan1, Zhijie Guo1, Limin Jia2
1Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, China.
Membranes
|September 27, 2023
Summary
The V-Ti-Co phase diagram was established, enabling the design of novel hydrogen-permeable alloys. The V23.5Ti50Co26.5 alloy shows record hydrogen permeability without embrittlement.
Area of Science:
- Materials Science
- Metallurgy
- Physical Chemistry
Background:
- The V-Ti-Co phase diagram is crucial for developing advanced hydrogen permeation alloys but remains unestablished.
- Understanding phase relationships is key to designing materials with specific hydrogen transport properties.
Purpose of the Study:
- To construct the first V-Ti-Co phase diagram using the CALculation of PHAse Diagrams (CALPHAD) method and experimental validation.
- To design and investigate hydrogen-permeable VxTi50Co50-x alloys based on the established phase diagram.
- To evaluate the microstructure and hydrogen transport behavior of these novel alloys.
Main Methods:
- CALculation of PHAse Diagrams (CALPHAD) approach for phase diagram construction.
- Experimental validation of the phase diagram.
- Alloy design based on phase diagram predictions.
- Microstructural characterization using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive Spectroscopy (EDS).
- Hydrogen transport behavior analysis.
Main Results:
- The first V-Ti-Co phase diagram was successfully constructed, featuring six ternary invariant reactions and eight phase regions.
- Hydrogen-permeable VxTi50Co50-x alloys were designed, with specific compositions (x = 17.5-23.5) showing high permeability.
- The alloy V23.5Ti50Co26.5 exhibited a record hydrogen permeability of 4.05 × 10-8 mol H2 m-1s-1Pa-0.5.
- High permeability is attributed to increased hydrogen solubility and diffusivity, influenced by Ti content in the (V, Ti) phase.
- The V-Ti-Co system demonstrates significantly higher permeability than Nb-TiCo and Nb-TiNi alloys.
Conclusions:
- The established V-Ti-Co phase diagram provides a foundation for designing high-performance hydrogen permeation alloys.
- VxTi50Co50-x alloys, particularly those with a TiCo phase and a eutectic structure, are promising candidates for hydrogen separation applications.
- The V23.5Ti50Co26.5 alloy represents a new benchmark for hydrogen permeability in this system, offering potential for advanced hydrogen technologies.
More Related Videos
Related Concept Videos
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
02:54Molecular and Ionic Solids
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
01:19Phase Diagram
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
01:27Two Components: Liquid–Liquid Systems
A pressure-composition phase diagram explicitly describes the behavior of an ideal solution of two volatile liquids under varying pressures and compositions. A pressure-composition diagram has two main curves. The bubble point curve represents the plot of pressure versus liquid mole fraction. It indicates the pressure at which the first bubble of vapor forms from the liquid phase as the system pressure decreases.The dew point curve is the pressure versus vapor mole fraction. It indicates the...
01:24Solid–Solid Solutions
The temperature-composition phase diagram of two solids, A and B, which are immiscible in the solid phase but form miscible liquids, shows that when the temperature is low, these two exist as separate, pure solids (A and B). As the temperature increases, they transition into a single-phase liquid solution where A and B coexist. Moving from point a1 to a2 in the phase diagram, the composition changes such that solid B begins to separate from the solution, enriching the remaining liquid with A.
01:28Phase Diagrams of Ternary Systems
Consider a ternary system, which is composed of three components: water (W), ethanoic acid (E), and trichloromethane (T). Here, Ethanoic acid (E) is fully miscible with both water (W) and trichloromethane (T), meaning it can mix entirely with either of them. However, water and trichloromethane have partial miscibility, meaning they can only mix to a certain extent, beyond which two separate phases will form.The phase diagram of a ternary system is represented as an equilateral triangle, where...