Steven J. Savage

Swedish Defence Research Agency · Sensor and EW Systems Department

The rheological and dynamic mechanical properties of polymer-based composites of Sm2Co17 and polyamide-12 with different particle loadings, sizes, and surface treatments are reported. Sm2Co17 particles were surface-treated with three different silanes: 3-glycidoxy(propyl)trimethoxysilane, 3-amino(propyl)trimethoxysilane (APTMS), and methyltrimethox...

There is an increasing demand for polymer-bonded magnets (PBM) in high temperature applications. While most research deals with high temperature properties of NdFeB–PBM, only a few studies consider Sm–Co PBM. Therefore, this study, on the thermal and magnetic properties of Sm–Co alloy powders and blends of these with polyamide-12 (PA12), was undert...

This paper discusses, compares, and contrasts the major rapid solidification techniques presently available. A table and flow chart are included to permit rapid comparison of the techniques to be made, and a glossary of terminology is appended. The methods have been separated into two major categories, those which involve drop formation (which enco...

The thermal stability of Sm2Co17 powders coated with four different silanes was studied between 25 °C and 500 °C and isothermally at 400 °C. Thermogravimetry data indicated that the silane-based coatings provided improved oxidation resistance. The microstructural analysis of uncoated powders oxidized for 10 h at 400 °C revealed the formation of a f...

Epoxy-based composites of ferrite nanoparticles (50 nm) with 3-glycidoxypropyl- (GPTMS), aminopropyl- (APTMS), or methyl-silsesquioxane (MTMS) coatings are reported. The GPTMS coatings (30-nm thick) allowed uniform particle dispersion in the epoxy and prevented sedimentation of the nanoparticles, whereas the APTMS-coated particles formed agglomerat...

The effects of silanising using the coupling agent γ-glycidoxpropyltrimethoxysilane on microstructural stability and magnetic properties of Sm-Co powder particles have been investigated. The silanisation provides structural stability by improving the oxidation resistance at 400oC for 10 hours. The untreated particles undergo microchemical changes b...

A rationale for rapid solidification processing of aluminum-lanthanide alloys is given, and preliminary results of microstructural studies on an aluminum-neodymium alloy are presented. Three distinct types of microstructure are seen in the as-cast rapidly solidified material, which are still evident after heat treatment at 350°C for 1 hour. Microha...

A series of (NixFeyAlz)0.9983B0.0017 (where x=58-60, y=13-15 and z=26-28, in at%) alloys have been rapidly solidified by - melt spinning. The ribbons have been characterized by HREM, DSC, X-ray diffraction and recoverable strain measurements. The as-cast alloys exhibit excellent bend ductility (in contrast to B2 type alloys conventionally cast) and...

Rapidly solidified (RS) Al-Er, Al-Nd, and Al-Gd ribbons were prepared by pendant drop melt extraction (PDME). The microstructures were studied in detail by optical and transmission electron microscopy. A wide range of microstructures are observed, including “conventional” RS type zones, a cellular structure surrounded by a degenerate eutectic and c...

The microstructures of ordered Ti//3Al-lZr (alpha//2 plus Zr) and Ti-Al-Nb alloys produced by ingot metallurgy (IM) and by rapid solidification (RS) are compared. The RS Ti//3Al-lZr (alpha//2 structure) alloy displayed small antiphase domains (APD) of 10-20 nm in the as-produced condition, but large grain size. The latter observation is rationalize...

An analysis of the microwave absorbing properties of several polymer-(epoxy) based nanocomposites is presented. The nanoparticles of interest for this study were cobalt ferrite nanoparticles. For better dispersion of the nanoparticles in the polymer matrix surface treatment of the nanoparticles with silane compounds was performed. The nanoparticles...

Scientists and engineers are actively engaged at the nanoscale in research and development of materials and surface coatings for defense applications. Advanced materials can be used for spectral design of surface reflectance and emittance. Both the composition and structure are important, in all wavelengths. By incorporating nanoporous beads that r...

The rapid solidification behavior of alloys in the Fe-Cr-Mn-Mo-Si-C system was investigated for different compositions and cooling rates. The C content was varied and alloying additions of Mo and B were studied with respect to their effect on the microstructure. The alloys were cast as either melt-spun ribbons or as 1-mm-thick plates after levitati...

A study of the microwave absorbing properties of polymer (epoxy) based nanocomposites is presented. The ferrite nanoparticles employed as filler materials were produced by a co-precipitation method, which was designed for production of large amounts at low cost. The absorbing properties of different kinds of ferrite nanoparticles, soft (manganese)...

The preparation of approximately 20 g cubic cobalt ferrite nanoparticles (edge length 30-60 nm) with composition CoxFe3-xO4 (0.85 center dot x center dot 1.00 +/- 0.02) using the co-precipitation method in a batch type reactor has been investigated. The morphology, composition, size and size distribution of the synthesized particles were characteri...

The influence of mixtures of Ni0.5Zn0.4Cu0.1Fe2O4, CoFe2O4, and graphite on the permeability, permittivity and microwave absorption properties in a composite embedded with insulating polymeric matrix, that can be used for X- and P-band radar absorption, has been investigated. Thermodynamic modelling of the complex ferrite system has been demonstrat...

The present paper addresses a possible route for the manufacturing of iron-based metal–matrix composites (MMCs) with a high level of reinforcement. The ceramic reinforcement studied was titanium carbide (TiC). TiC is one of the hardest materials to be found, which is why a TiC/Fe composite has the potential to be used as armour. Two manufacturing r...

In the first part of this paper, a new method is shown which is able to predict the particle size of conductive nanoparticle films in situ, during deposition. The method is used for the measurement of the time-derivative of conductance fluctuations during deposition. The second part of the paper deals with in situ conductance measurements on gold f...

Measurements are reported of the elastic constants of single-crystal yttrium in the range of temperature 4-300K. Single-crystal samples, with a range of impurity contents, were obtained from a rod that had been subjected to solid state electrotransport. This allowed a study of the dependence of elastic constants on concentration of impurity and per...

The mechanical behaviour of a nitrogen alloyed steel has been investigated. Tensile tests have been done at nominal strain rates from 10-3to 800 s-1. The results are discussed in terms of material rnodelling and constitutive parameters for the Johnson and Cook model are proposed. At large strain rates the effect of adiabatic heating complicates the...

We have in this report considered some types of material with potential for use in signature control of structures. The material types selected for inclusion in this study were electrically conductive polymers, fullerenes, nanostructured materials and Langmuir-Blodgett films. To control the signature of a structure in real time it must be possible...

Two NiFeAlB alloys, solidified into ribbons by melt spinning, were characterized by HREM, DSC, X-ray diffraction and recoverable strain measurements. The as-cast alloys exhibit excellent bend ductility (in contrast to B2-type alloys prepared by conventional casting). X-ray diffraction shows the presence of β-NiAl, β′-NiAl, γ-Ni3Al, γ′-Ni3Al, Ni...

Austenitic stainless steels are used in a wide range of applications because of their excellent corrosion resistance as well as cold formability. For many applications, however, there is a demand for increased strength and retained corrosion resistance.

Rapidly solidified ribbons (∼ 40 μ thich) have been produced by melt spinning. The alloys studied have the composition (NixFeyAlz)0.9983B0.0017, where x = 58−60, y = 13−15, and z = 26−28 (at.%). The ribbons have been characterized by thermal analysis (DSC), X-ray diffraction analysis and microstructural analysis. Heat treatment and recoverable stra...

Powders from Fe16Cr8Mo18CC-4B and Fe16Cr8Mo18C4V (at.%) which have been produced by high pressure helium atomization are mainly amorphous below 25 μm diameter. These powders have been consolidated to full density by uniaxial hot pressing at 1080°C. The alloys crystallize during consolidation and form structures with finely dispersed carbide...

The phase constitution and magnetic properties of ribbons in the system Nd_0.15(Fe_0.935-x M _xB_0.065)_0.85, where M =Nb, Si, and Ga, and 0&les; x &les;0.06, have been investigated by X-ray diffraction, magnetic balance, and vibrating sample magnetometer measurements. The Curie temperature, T <sub...

A theoretical analysis of the origin of residual stresses in amorphous wires and their effect on the magnetostrictive properties has been made. The residual stress distribution (compression in the surface and tension in the center) in the wire is attributed to the different cooling rates experienced during solidification by different regions of the...

Fe-Si wires with circular cross-sections have been cast directly from the melt by the in-rotating water melt spinning process. The Fe-Si wires with 4-6 wt% Si are ductile while Fe-7 wt% Si shows partial ductility. In the as-solidified state, the microstructure is cellular or dendritic. After annealing at 1000°C for 1 hour, a bamboo-like structure i...

A modified corrosion resistant stainless steel has been directly cast into rapidly solidified wires of 130–150 μm diameter by the in-rotating-water melt spinning process. The microstructure, mechanical properties and corrosion resistance have been characterized by optical and transmission electron microscopy, X-ray diffractometry, tensile testing a...

Fluid flow behavior during ultrasonic gas atomization was studied. Gas velocity was measured by pilot tube experiments and Schlieren photography. Powder particle velocities were calculated. The gas velocity reaches 1700 m/s (Mach 1,7) in the supersonic flow region for helium gas at a backing pressure of 6,9 MPa. A 15 mu m diameter Al-5mass% Mn-2,5m...

A series of consolidation experiments of ultrasonically helium atomized Al-5Mn-2.5Cr (all composition in wt.% unless otherwise indicated) and Cu-0.5Zr alloys have been performed. The powders were produced and handled under inert gas, canned, evacuated and consolidated by cold isostatic pressing followed by hot extrusion. The extrusion parameters, i...

Direct wire casting by “in-rotating-water melt spinning” has opened up a new future for the production of rapidly solidified wires. The process is unique in that wires of circular cross-section are formed in a single-step process by ejecting the molten metal into a moving water layer.Experiments with a wide range of alloys have shown that the conti...

Fluid flow behaviour during ultrasonic gas atomization was studied. The gas velocity was determined by total pressure measurement and Schlieren photography, and the metal powder particle velocity was calculated. The gas velocity reaches about 1700 m s−1 (Mach. 1.7) in the supersonic flow region for helium gas at a backing pressure of 6.9 M Pa. An A...

A precipitation-hardened titanium-modified 316L stainless steel has been prepared by hot extrusion of nitrided rapidly solidified powder. The microstructure and properties of the rapidly solidified powder, internally nitrided powder and extruded bulk material have been investigated. The microstructure of extrudates consists of fine austenite grains...

Two 316L austenitic stainless steel alloys were prepared as rapidly solidified powders by high pressure inert gas atomization. The alloys were modified by the addition of 0.7 wt% titanium, but otherwise the compositions were within ASTM specifications. After sieving the atomized powders, it was observed that the smaller size fractions in one alloy...

Metastable Al//4Gd has been identified as the intercellular phase in as-cast rapidly solidified ribbon. Rapid coarsening of the microstructure is seen at 500 degree C, and after 1 hour the microstructure is completely spheroidized, with second phase particles of 1 mu m or greater in size distributed at the grain boundaries. A 40 pct increase in har...

This book contains over 40 selections. Some of the titles are: Dispersion strengthened Al-Fe-Si alloys containing V, Mn, Cr or Mo; Powder size distribution and heat treatment effects on the hardness of Al-Fe-Ce-W alloy; Consolidation and properties of thermally stable Al-Cr-Zr alloys produced by rapid solidification; and Feasibility of rapid solidi...

earths (Nd-rich), 0.5wt%Zr, balance magnesium, and achieves optimum room and elevated-temperature strengths through Solution heat treatment and artificial ageing. Although WE54X is reportedly weldable using the gas tungsten-arc welding process [1], recent laser welding trials have indicated that it may be sensitive to heat-affected zone liquation c...

The results of a study of the microstructures developed in a rapidly solidified Al-Gd alloy are presented. A metastable precipitate with potential as a high temperature dispersion strengthening phase was found after artificial aging. This precipitate is spherical, semi-coherent, 20-40 nm diameter, and apparently stable to an exposure at 450 degree...

A process and apparatus for continuously casting a castable material to a thickness of 10 to 40 mils is discussed. A molten material is first spread onto a spreading roller to a uniform thickness and then transferred to a quenching roller whereon the material is cooled until dimensionally stable. The apparatus may be employed to continuously cast t...

The design and operation of equipment to generate rapidly solidified samples in batches as large as 5 kg, under closely controlled atmosphere conditions, is described. Two modes of operation are possible at present: gas atomization-substrate solidification (GASS) and crucible melt extraction (CME). Both produce particulate, the former with a flake...

The anomalous dip in c33 for Gd at 240 K, where the magnetic moments rotate away from the hexagonal axis, has been remeasured with the high purity samples now available. It is found that the dip is at least five times smaller than previously reported experimentally and also considerably smaller than theoretically estimates based on magneto-elastic...

A series of rapidly solidified aluminum-lanthanide (A1-LA) binary alloys are being studied at AFWAL Materials Laboratory to determine microstructures, thermal stability, hardness and second phase identity. Alloys prepared by pendant drop melt extraction (PDME) were cast, heat treated and characterized by optical, electron microscopy and X-ray diffr...

Rapid solidification of Mg-Ca base alloys provides excellent hardness-to-density ratios in combination with Cu and Ni which are retained for 1h up to 200 degree C. The hardness increments are associated with a refined microstructure and might be related to the glass forming ability of these ternary systems. The latter might also be responsible for...

Thesis (Ph. D.)--University of Hull, 1982.