Related Experiment Video
Updated: May 26, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
The phase transition in annealed mechanically alloyed Fe - Cu
1Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, People's Republic of China. Centre for Advanced Studies in Science and Technology of Microstructures, Nanjing 210093, People's Republic of China.
Summary
Annealed iron-copper alloys show phase transformations. Milling induces metastable fcc-Fe and fcc-Cu phases, which revert to stable bcc-Fe and fcc-Cu upon annealing, depending on conditions.
Area of Science:
- Materials Science
- Metallurgy
- Solid-State Physics
Background:
- Mechanical alloying is a technique used to produce homogeneous mixtures of otherwise immiscible elements.
- Iron-copper (Fe-Cu) alloys are of interest due to their unique magnetic and structural properties.
Purpose of the Study:
- To investigate the phase transformations in mechanically alloyed Fe-Cu during annealing.
- To characterize the structural evolution of Fe-Cu alloys after milling and subsequent heat treatments.
Main Methods:
- Mössbauer spectroscopy was employed to analyze the magnetic and chemical environment of Fe atoms.
- X-ray diffraction (XRD) patterns were used to determine the crystallographic phases present.
Main Results:
- Milling of Fe-Cu alloys resulted in the formation of face-centered cubic (fcc) copper (Cu) transforming to body-centered cubic (bcc) Cu, with Cu diffusion into iron (Fe).
- Annealing caused the bcc-Cu to revert to fcc-Cu, and Cu atoms in Fe to separate. An fcc-Fe-rich phase formed after milling transformed back to bcc-Fe upon annealing.
- Transformation kinetics were influenced by milling time and annealing temperature; shorter milling and higher annealing temperatures accelerated the fcc-Fe to bcc-Fe transformation.
Conclusions:
- The fcc-Fe-rich phase in milled Fe-Cu is metastable and transforms to stable bcc-Fe upon annealing.
- The fcc-Cu-rich phase formed after prolonged milling is stable and persists through annealing.
Related Concept Videos
02:32Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
02:33Phase Transitions: Sublimation and Deposition
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
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...
01:21Phase Transitions
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
02:31Phase Transitions
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to occupy...
01:18Mechanical Characteristics of Steel
The mechanical characteristics of steel are assessed through various tests that evaluate its strength, toughness, and flexibility. These tests include tension, torsion, impact, bending, and hardness assessments, each providing crucial information about steel's suitability for specific applications.
The tension test is fundamental for determining tensile strength. In this test, a steel specimen is stretched using a gripping device until it breaks. The data collected during this test are used to...
The tension test is fundamental for determining tensile strength. In this test, a steel specimen is stretched using a gripping device until it breaks. The data collected during this test are used to...