Abstract: The present invention provides magnetostrictive composites that include an oxide ferrite and metallic binders which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

Abstract: The present invention provides Terfenol-D alloys (“doped” Terfenol) having optimized performances under the condition of time-dependent magnetic fields. In one embodiment, performance is optimized by lowering the conductivity of Terfenol, thereby improving the frequency response. This can be achieved through addition of Group III or IV elements, such as Si and Al. Addition of these types of elements provides scattering sites for conduction electrons, thereby increasing resistivity by 125% which leads to an average increase in penetration depth of 80% at 1 kHz and an increase in energy conversion efficiency of 55%. The permeability of doped Terfenol remains constant over a wider frequency range as compared with undoped Terfenol. These results demonstrate that adding impurities, such as Si and Al, are effective in improving the ac characteristics of Terfenol.

Abstract: The present invention provides magnetostrictive compositions that include an oxide ferrite which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

Abstract: Apparatus and method for measuring the Barkhausen signal of a moving magnetic film, ribbon or fiber wherein first and second stationary electromagnet coils are arranged and separated by a distance, d, along the path of movement of the film, ribbon or fiber. The first and second coils are energized in a manner to generate first and second opposing DC magnetic fields through which the moving film, ribbon or fiber passes along its path of movement. As the film, ribbon or fiber moves through the first and second opposing magnetic fields at a velocity, v, it experiences one complete cycle of magnetization in a period of time equal to d/v. A stationary third signal pick-up coil is disposed between the first and second coils to detect the Barkhausen signal from the moving film, ribbon or fiber. The pick-up coil typically is disposed midway between the first and second coils where the Barkhausen signal will be approximately maximum.

Abstract: A magnetic inspection head adapted for use with samples having non-planar surfaces. A magnetically permeable core has a pair of poles joined by a magnetically permeable bridge to form a closed magnetic circuit between the pole legs, bridge and the test material. Each pole has magnetically permeable support means terminating in a magnetically permeable deformable surface for engaging the sample. The support means is yieldable such that when the inspection head is placed in contact with the irregular surface of the sample, the deformable surface is deformed to accommodate the shape of the sample with minimal air gaps therebetween. Preferably, the deformable surface is provided by a plurality of pins slidably engaged in a pole structure and urged outwardly for contact with and conformance with a non-planar sample surface.

Abstract: A magnetic inspection probe for use in the planar measurement of magnetic properties in two or more defined directions. The inspection probe includes a cup-shaped outer body, a centrally disposed central core, a field generating power coil, a flux coil for measuring magnetic induction and a plurality of field detection elements disposed in various known orientations. In use, the inspection probe of the present invention permits the detection and measurement of anisotropy of material characteristics in at least two directions across the plane of measurement.

Abstract: A multiparameter magnetic imaging system and method to be used in the localized measurement of the magnetic properties of a material and the display of those properties in the form of a false color image indicating the occurrence of those properties across the surface of a sample specimen. The system includes an inspection probe to measure certain magnetic parameters across the surface of the specimen and means to determine a multiplicity of magnetic property values based on the measured data. The system also includes a visual display system which selectively displays the data relating to the determined magnetic properties in the form of a false color image indicating the presence and variation of these magnetic properties across the specimen surface.

Abstract: A system and a related method for non-destructive evaluation of the surface characteristics of a magnetic material. The sample is excited by an alternating magnetic field. The field frequency, amplitude and offset are controlled according to a predetermined protocol. The Barkhausen response of the sample is detected for the various fields and offsets and is analyzed. The system produces information relating to the frequency content, the amplitude content, the average or RMS energy content, as well as count rate information, for each of the Barkhausen responses at each of the excitation levels applied during the protocol. That information provides a contiguous body of data, heretofore unavailable, which can be analyzed to deduce information about the surface characteristics of the material at various depths below the surface.

Abstract: A magnetometer which employs a rod of magnetostrictive material comprising a ternary alloy of dysprosium, terbium and iron wherein the grains of the material have their common principal axes substantially pointed along the axis of the rod. Means are provided for compressively stressing the rod in order to enhance the magnetostrictive response thereof. A laser source and photosensor are associated with a free end of the rod to function as an external cavity laser sensor. A DC magnetic bias is required for the magnetostrictive rod in order to operate in the sensitive range of the magnetostrictive characteristics of the rod. In a portable implementation of the device, the DC bias is provided by means of permanent magnets, preferably rare earth magnets, in order to provide the high bias fields compatible with high sensitivity of the material in a miniaturized portable device.

Abstract: A non-destructive evaluation technique for deriving stress in ferromagnetic materials including deriving anhysteretic and hysteresis magnetization curves for the material in both unstressed and stressed states. The anhysteretic curve is expressed as a Langevin function. The stress is expressed as an equivalent magnetic field dependent on stress and change of magnetostriction with magnetization. By measurement of these bulk magnetic properties, stress can be derived.

Abstract: A multiparameter magnetic inspection system for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen.

Abstract: A method is disclosed for detecting the T.sub.1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T.sub.1 phase may be detected.