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From pots and pans on the stove to bridge suspension cables, metal composites need to take into account a variety of strength, malleability and durability to meet human needs. Researchers at the Nagoya Institute of Technology (NITech) in Japan applied three-dimensional crystallography to visualize how individual particles shape composites – and how they could be manipulated to get better versions.
"The strength of the composite depends on the size, spatial distribution and three-dimensional shape of the particles," said Dr. Hisashi Sato, associate professor at the Graduate School of Engineering and the Institute for Materials Research for the science of materials. He collaborated with Professor Yoshimi Watanabe on this research.
In the manufacture of composites, such as the drawing of metal alloys for the manufacture of bridge suspension wires, the materials are pressed and stressed to separate the particles. The particles are then driven into a finer rearrangement, but they must be carefully controlled to avoid losing strength or becoming brittle. This process, called equal channel angulation (ECAP), is called "deformation" of the composite particles from their original state.
According to Dr. Sato, no one has examined the change in particle distribution by images in the three-dimensional deformed composite. Professors Sato and Watanabe used 3D microstructural observation and crystallographic analysis to study shape, size, and particle placement changes in aluminum-based composites.
They found that the deformed fragments were redistributed on how the underlying matrix – scaffold – of the composite was split and replaced, such as particles reorganizing when the suspension wire was pulled because the surface was reduced. . More than that, Mr. Sato stated that the particle distribution in the deformed composite could actually be controlled according to the material flow of its matrix.
The researchers also investigated the effects of shear patterns or change in the direction of the sample for each ECAP pass. In the attached figure, track A is the case of a non-rotating specimen, track Bc is the case of a 90-degree rotation and track C is the case of a 180-degree rotation with 4 passes. . They discovered that Route Bc produces the smallest particle fragment Al-Al3Ti. It is believed that the Al3Ti intermetallic particle preferentially breaks up at a specific location in the deformation process, providing another level of control to create a better grain.
According to Dr. Sato, researchers have already found that the deformation process of the Al-Al3Ti composite allowed better refining of the A1 molding grain, but they did not understand the mechanisms underlying the improved results. Researchers and engineers can now design a better grain refiner for pouring aluminum with precise control.
"The strength and ductility of the metal composite is highly dependent on the size and spatial distribution of the particle," said Dr. Sato. "Understanding the relationship between particle size, particle spatial distribution and composite mechanical properties is important for designing the composite with superior strength and ductility."
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Material provided by Nagoya Institute of Technology. Note: Content can be changed for style and length.
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