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From cooling to heat treatment: What surprising secrets are hidden in the manufacturing process of materials?
In the field of materials science, crystalline texture refers to the crystallographic orientation distribution of polycrystalline samples. When these orientations are completely random, or when the sample is in an amorphous state, it is said to be "textureless." However, when a preference exists for crystallographic orientation, the sample may have varying degrees of texture, ranging from weak to strong, depending on the percentage of crystals possessing that preferred orientation.
This article will delve into how crystalline textures affect material properties, their presence in various engineering materials, and how to adjust these textures through heat treatment to obtain desired material properties.
Texture can be observed in almost all engineering materials and has a great influence on the performance of the material.
Formation of crystalline texture
During thermodynamic processing of materials, such as rolling during production, crystalline textures can form. After the rolling process, a heat treatment is often performed to reduce unwanted texture. Controlling the production process combined with characterization of texture and material microstructure helps determine material properties, i.e., processing-microstructure-texture-property relationships.
Whether it is a geological rock or a metallic material, the formation of texture is related to its thermomechanical history. The orientation of the crystal will affect how the material performs in everyday applications. For example, a completely random crystallographic orientation would result in a material with isotropic properties over sufficiently large length scales, whereas a perfect single crystal might exhibit anisotropic properties due to geometric necessity.
Characterization and characterization of crystalline texture
Texture can be determined by a variety of methods, some of which allow quantitative analysis, while others allow only qualitative analysis. Among the quantitative techniques, the most widely used is X-ray diffraction using texture goniometers, followed by the electron backscattered diffraction (EBSD) method in scanning electron microscopy. Qualitative analysis can be performed by Roche photography, simple X-ray diffraction or polarization microscopy.
Texture is often represented using a pole figure, in which the designated crystallographic axes derived from each representative grain are plotted in a stereographic projection.
Common texture types include cubic components, copper components, etc. These types are often found in processed solid materials. These textures are often named after Miller indices for easier expression and understanding.
The relationship between texture and material properties
Material properties such as strength, chemical reactivity, resistance to stress corrosion cracking, weldability, deformation behavior and resistance to radiation damage may be highly dependent on the material's texture and related microstructural changes. The properties of many materials are specific to their texture, so an unfavorable texture that occurs during the material's manufacture or use can cause weaknesses and cause failure.
Evolution of film texture
Thin film materials occupy an important position in many modern technological devices, such as microelectronics, optoelectronic systems and superconducting layers. Film textures can generally be divided into two categories: fiber textures and bidirectional textures. The manipulation of this texture is crucial to meet technical requirements. For example, in transparent conductive films, obtaining a specific polar axis is critical to the material's performance.
The texture evolution during film growth requires precise control to ensure that the properties of the final product meet requirements.
The production process and public application of these materials are not only technical challenges, but also involve a deep understanding of texture evolution, which are important considerations for future material design and applications.
What more secrets might be hidden in the properties of materials from cooling to heat treatment?
