The Piezomagnetic Matteucci Effect in Nickel Alloys: Development of Theory and Applications

该项目为描述马特乌奇现象奠定了基础。这项研究集中在一种相对简单的材料，称为坡莫合金，在这种材料中，磁致伸缩可以通过合金成分来控制。该项目包括样品制备、结构表征和测量在不同温度和磁场强度下扭转应力下的磁性变化。这项工作将首先建立一个原则性、非线性、滞后性的现象理论模型。镍是提供一组可靠的基本数据的主要选择材料；与其他磁性材料相比，它具有许多优势，因为它具有相对较高的磁致伸缩、低各向异性和对外加应力的高敏感性。此外，沿100和111方向的磁致伸缩系数是可比较的，导致磁致伸缩对场的依赖关系更简单。镍和铁可以合金化，制备出磁致伸缩系数从+7ppm到-35ppm的一系列材料，从而可以测试材料的磁弹性特性对响应的依赖关系。所有这些因素在寻找描述材料观察到的行为的模型方面都是一个优势。这项工作将记录一个相对简单的磁性系统在扭转应力作用下的行为，将检查这些材料在各种实验条件下对扭矩的磁性响应，并将开发出帮助我们理解材料性能的模型方程。由于寻找磁性扭矩传感器的材料，Matteucci效应，即具有扭转应力的材料的磁化强度的变化，目前引起了极大的技术兴趣。材料的磁性，特别是磁化强度，对应力非常敏感，但从科学的观点来看，这种行为很难理解。这是因为马特乌奇效应是非线性的和路径依赖的(滞后的)。目前还没有足够的理论可以用来准确地描述这种行为。

This project lays the groundwork for a description of the Matteucci phenomenon. The research concentrates on one relatively simple class of materials known as permalloys in which magnetostriction can be controlled via the alloy composition. The project includes specimen preparation, structural characterization, and measurements of the changes in magnetic properties under torsional stress at different temperatures and magnetic field strengths. The work will develop a first principles, non-linear, hysteretic, theoretical model of the phenomenon. Nickel is the main material of choice for providing a reliable set of basic data; it has many advantages over other magnetic materials because of its relatively high magnetostriction, low anisotropy and high sensitivity to applied stress. In addition the magnetostriction coefficients along the 100 and 111 directions are comparable, resulting in a simpler dependence of magnetostriction on field. Nickel can be alloyed with iron to produce a series of materials with magnetostriction coefficients ranging from +7 ppm to -35 ppm, so that the dependence of the response on the magnetoelastic properties of the materials can be tested. All of these factors are an advantage in the search for a model to describe the observed behavior of the materials. This work will document the behavior of a relatively simple magnetic system under the action of torsional stress, will examine the magnetic response of these materials to torque under a variety of experimental conditions, and will develop model equations that help us to understand the performance of the material. %%%The Matteucci effect, that is the change of magnetization of a material with torsional stress, is currently of great technological interest because of the search for materials for magnetic torque sensors. Magnetic properties of materials, particularly magnetization, are very sensitive to stress, and yet this behavior is poorly understood from a scientific viewpoint. This is because the Matteucci effect is non-linear and path dependent (hysteretic). At present there is no adequate theory that can be used to accurately describe this behavior.***