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Amorphous or glassy metals are a unique class of materials that typically exbibit higher strengths than their crystalline counterparts but have limited ductility. Mechanical alloying (MA) of metal powders offers the possibility of forming metallic glasses for a large range of systems. Unfortunately, consolidation of the powder to bulk form usually results in crystallization of the amorphous phase. Previous research has shown that MA can produce a W-Ni-Fe amorphous powder with remnant nanocrystalline W particles in the glassy matrix. The goal of this research was to consolidate mechanically alloyed W-Ni-Fe powders to near or full density without causing crystallization of the W-Ni-Fe glassy phase. A systematic study on the consolidation of the most thermally stable alloy was conducted using different consolidation techniques and binder materials. Experiments were designed to examine the effects of different processing parameWrs including: temperature, pressure, time, and binder amount. The experimental results showed that it was possible to consolidate the MA W-Ni-Fe to a calculated density of 98 to 99% while retaining the glassy/amorphous structure. The process involved MA elemental Cu powder with the MA W-Ni-Fe powder and consolidating the composiW powder by Rapid Sinter Forging (RSF). Pressure was identified as the dominant processing parameter for densification. Temperature's effect on densification was minimal but important for crystallization of the glass.

Relationships among the synthesis, processing, structure and properties of materials generated through mechanical alloying (MA) or mechanosynthesis are described. Several materials classes: cermets, particulate metal matrix composites (MMC), and tungsten heavy alloys (WHA) have been produced, and their properties and structures evaluated. Niobium carbide and tungsten, carbide cermets can be conveniently generated either through room temperature synthesis (NbC cermets) or by room temperature milling followed by elevated temperature exposure (WC cermets). Cermet microstructures following consolidation are fine, and the materials demonstrate exceptional hardnesses albeit their fracture toughnesses are generally low. Al based MMC can be synthesized similarly. The composites we have studied utilize aluminum carbide as a reinforcement. The yield strengths of these MMC are approximately twice those of high strength aerospace Al alloys. Noncrystalline WHA can be generated via MA. During consolidation, these alloys are prone to crystallization. Nonetheless, because of their fine structure the crystalline products manifest high hardnesses relative to conventional WHA. Current efforts are focusing on retaining the noncrystalline phase during consolidation so as to produce materials having particularly desirable mechanical properties.

This report summarizes results of several areas of research dealing with mechanical alloying of materials having potential structural use. The areas involve modeling of the process, synthesis of unique materials via mechanical alloying and consolidation of mechanically alloyed products. The latter area is one receiving most current attention as consolidation involves high temperatures and (usually) pressures. This can lead to a 'loss' of the unique structures produced by mechanical alloying. Thus, consolidation studies attempt to produce fully dense material maintaining many of the desirable properties manifested by mechanically alloyed powders.

Multiple shear banding is observed in metallic glasses during tensile deformation of laminated composites containing such glasses. The phenomenon is related to (1) the local stress concentration that develops as a result of the formation of the first shear band, (2) the distribution in stress required to initiate shear banding in tensile loading, and (3) the properties of the surrounding matrix. The tendency for localized and uniform multiple shear banding has been determined. This was done by utilizing a finite element method (FEM) to simulate the local stress state in the vicinity of the shear band first formed, and by determining the distribution in shear band initiation strengths. The experimental data were combined with the FEM analysis to "predict" locations of secondary shear band initiation. Localized secondary banding is predicted for large initial slip displacements, whereas uniform banding is expected when the initial slip displacement is small.

Multiple shear banding is observed in metallic glasses during tensile deformation of laminated composites containing such glasses. The phenomenon is related to (1) the local stress concentration that develops as a result of the formation of the first shear band, (2) the distribution in stress required to initiate shear banding in tensile loading, and (3) the properties of the surrounding matrix. The tendency for localized and uniform multiple shear banding has been determined. This was done by utilizing a finite element method (FEM) to simulate the local stress state in the vicinity of the shear band first formed, and by determining the distribution in shear band initiation strengths. The experimental data were combined with the FEM analysis to "predict" locations of secondary shear band initiation. Localized secondary banding is predicted for large initial slip displacements, whereas uniform banding is expected when the initial slip displacement is small.

Multiple shear banding is observed in metallic glasses during tensile deformation of laminated composites containing such glasses. The phenomenon is related to (1) the local stress concentration that develops as a result of the formation of the first shear band, (2) the distribution in stress required to initiate shear banding in tensile loading, and (3) the properties of the surrounding matrix. The tendency for localized and uniform multiple shear banding has been determined. This was done by utilizing a finite element method (FEM) to simulate the local stress state in the vicinity of the shear band first formed, and by determining the distribution in shear band initiation strengths. The experimental data were combined with the FEM analysis to "predict" locations of secondary shear band initiation. Localized secondary banding is predicted for large initial slip displacements, whereas uniform banding is expected when the initial slip displacement is small.

A finite element model (FEM) analysis has been conducted to evaluate ineffective lengths in metal matrix composites. The results are compared with those of a modified analytical treatment based on a previous analysis of Rosen. Ineffective lengths obtained by both treatments are in good agreement, but differ considerably from those predicted by Rosen's original formulation. The influence of different boundary loading conditions at the fiber end on the efficiency of stress transfer to the fiber has also been investigated by the FEM. In addition, an elastic-plastic FEM analysis has been used to study the influence of matrix plastic deformation on ineffective lengths. As is also discussed, the FEM approach may be useful for defining criteria for delamination at the fiber-matrix interface.

The crack growth behavior of metallic glass in laminated metal-metallic glass composites was investigated and compared to the crack growth characteristics of monolithic metallic glass. The composite arrangement significantly increases the crack growth resistance of the glass. Growth in the monolithic glass is catastrophic, whereas in the composite, it is stable. The behavior is described in terms of crack growth resistance (R) curves and discussed in terms of extrinsic and intrinsic contributions to toughness. It is found that an extrinsic factor, i.e., matrix bridging, makes the major contribution to increased crack growth resistance and that a limiting crack opening displacement model interprets the experimental data quite well. Enhanced glass deformation in the crack tip region, manifested by multiple shear band formation, is responsible for the intrinsic toughening observed. Physical models are developed to estimate the level of intrinsic toughening due to this effect.

The crack growth behavior of metallic glass in laminated metal-metallic glass composites was investigated and compared to the crack growth characteristics of monolithic metallic glass. The composite arrangement significantly increases the crack growth resistance of the glass. Growth in the monolithic glass is catastrophic, whereas in the composite, it is stable. The behavior is described in terms of crack growth resistance (R) curves and discussed in terms of extrinsic and intrinsic contributions to toughness. It is found that an extrinsic factor, i.e., matrix bridging, makes the major contribution to increased crack growth resistance and that a limiting crack opening displacement model interprets the experimental data quite well. Enhanced glass deformation in the crack tip region, manifested by multiple shear band formation, is responsible for the intrinsic toughening observed. Physical models are developed to estimate the level of intrinsic toughening due to this effect.

A finite element model (FEM) analysis has been conducted to evaluate ineffective lengths in metal matrix composites. The results are compared with those of a modified analytical treatment based on a previous analysis of Rosen. Ineffective lengths obtained by both treatments are in good agreement, but differ considerably from those predicted by Rosen's original formulation. The influence of different boundary loading conditions at the fiber end on the efficiency of stress transfer to the fiber has also been investigated by the FEM. In addition, an elastic-plastic FEM analysis has been used to study the influence of matrix plastic deformation on ineffective lengths. As is also discussed, the FEM approach may be useful for defining criteria for delamination at the fiber-matrix interface.

The crack growth behavior of metallic glass in laminated metal-metallic glass composites was investigated and compared to the crack growth characteristics of monolithic metallic glass. The composite arrangement significantly increases the crack growth resistance of the glass. Growth in the monolithic glass is catastrophic, whereas in the composite, it is stable. The behavior is described in terms of crack growth resistance (R) curves and discussed in terms of extrinsic and intrinsic contributions to toughness. It is found that an extrinsic factor, i.e., matrix bridging, makes the major contribution to increased crack growth resistance and that a limiting crack opening displacement model interprets the experimental data quite well. Enhanced glass deformation in the crack tip region, manifested by multiple shear band formation, is responsible for the intrinsic toughening observed. Physical models are developed to estimate the level of intrinsic toughening due to this effect.

A finite element model (FEM) analysis has been conducted to evaluate ineffective lengths in metal matrix composites. The results are compared with those of a modified analytical treatment based on a previous analysis of Rosen. Ineffective lengths obtained by both treatments are in good agreement, but differ considerably from those predicted by Rosen's original formulation. The influence of different boundary loading conditions at the fiber end on the efficiency of stress transfer to the fiber has also been investigated by the FEM. In addition, an elastic-plastic FEM analysis has been used to study the influence of matrix plastic deformation on ineffective lengths. As is also discussed, the FEM approach may be useful for defining criteria for delamination at the fiber-matrix interface.

[2], 6 p., Signed: Thomas Courtney., Reproduction of original in Thomason Collection, British Library., (DLPS) A34777.0001.001, (stc) Wing C6611, http://quod.lib.umich.edu/t/text/accesspolicy.html, To the extent possible under law, the Text Creation Partnership has waived all copyright and related or neighboring rights to this keyboarded and encoded edition of the work described above, according to the terms of the CC0 1.0 Public Domain Dedication (http://creativecommons.org/publicdomain/zero/1.0/). This waiver does not extend to any page images or other supplementary files associated with this work, which may be protected by copyright or other license restrictions. Please go to http://www.textcreationpartnership.org/ for more information.

[2], 6 p., Signed: Thomas Courtney., Reproduction of original in Thomason Collection, British Library., (DLPS) A34777.0001.001, (stc) Wing C6611, http://quod.lib.umich.edu/t/text/accesspolicy.html, To the extent possible under law, the Text Creation Partnership has waived all copyright and related or neighboring rights to this keyboarded and encoded edition of the work described above, according to the terms of the CC0 1.0 Public Domain Dedication (http://creativecommons.org/publicdomain/zero/1.0/). This waiver does not extend to any page images or other supplementary files associated with this work, which may be protected by copyright or other license restrictions. Please go to http://www.textcreationpartnership.org/ for more information.

The tensile properties of brass (Cu-30% Zn)-nickel base metallic glass (MBF-35 Metglas) laminates have been investigated. Laminates were prepared by soldering these constituents together with a Pb-Sn alloy. The metallic glass exhibited an enhanced tensile ductility in the metal matrix environments, and such enhanced ductility depended on the metal matrix strength and elongation. Multiple shear bands have been observed in the metallic glass ribbon with enhanced tensile ductility. The failure modes of the laminates have been analysed based on stress-strain concentration concepts, following failure of the glass. The results were consistent with the experimental observations.

This paper discusses the potential of NiW alloys of differing initial microstructures, for high-strain cold deformation processing, and thus their suitability for development as heavily deformed, high strength in situ composites. Varying initial phase morphologies and tungsten volume fractions were produced by variations in initial processing. Liquid-phase sintered structures, containing 48 vol.% W, can be cold rolled to true strains of 2.4. They presumably could be cold worked further, but size limitations imposed by our processing capability prevented that being done in this study. Likewise, low volume fraction (of less than 15 vol.%) tungsten alloys, produced by casting of a hypoeutectic nickel-rich alloy and by transient liquid-phase sintering, can be cold rolled to the same strain as the liquid-phase sintered NiW structure. In contrast, as-cast arc melted alloys cannot be cold drawn to any extent at room temperature. They can be made capable of limited drawability by subjecting them to a coarsening heat treatment, which also spheroidizes eutectic tungsten to some extent, prior to cold working. The limited malleability of this alloy appears to be related to the heterogeneous distribution of nondeforming tungsten particles. Fracture surfaces of material that failed during drawing are populated heavily by such particles. The strengths of cold worked NW alloys of the present study exceed those of comparably deformed directionally solidified NiW eutectic alloys, at least up to deformation strains of 2.4. Since the latter type of alloy manifests extensive work hardening for deformation strains greater than 3.0, we expect this would also hold for the alloys described in this paper. Thus the NiW system, composed of a strong, tough nickel phase and a linear work hardening tungsten phase, is a likely candidate for development as a strong, tough, heavily deformed in situ composite.

The capillary shape instabilities associated with ribbon or finite plate dispersoids are described and documented with experimental evidence from three composite systems: (1) drawn castings of CuFe containing ribboned Fe fibers (14.3 vol.% Fe), (2) rolled liquid-phase sintered NiW alloys containing elliptic W plates (48 vol.% W), (3) rolled "hypoeutectic" NiW alloys containing W blades which occupy 17% of the eutectic microconstituent's volume. The primary instabilities observed include cylinderization via edge recession, boundary splitting via the thermal grooving of internal boundaries, and edge spheroidization via the ovulation of ridges formed by edge recession. For a given plate-shaped dispersoid, the dominant instability is determined by cross sectional aspect ratio (width/thickness) and, when internal boundaries are present, the ratio of the internal boundary's energy to that of the phase interface.

This paper discusses the potential of NiW alloys of differing initial microstructures, for high-strain cold deformation processing, and thus their suitability for development as heavily deformed, high strength in situ composites. Varying initial phase morphologies and tungsten volume fractions were produced by variations in initial processing. Liquid-phase sintered structures, containing 48 vol.% W, can be cold rolled to true strains of 2.4. They presumably could be cold worked further, but size limitations imposed by our processing capability prevented that being done in this study. Likewise, low volume fraction (of less than 15 vol.%) tungsten alloys, produced by casting of a hypoeutectic nickel-rich alloy and by transient liquid-phase sintering, can be cold rolled to the same strain as the liquid-phase sintered NiW structure. In contrast, as-cast arc melted alloys cannot be cold drawn to any extent at room temperature. They can be made capable of limited drawability by subjecting them to a coarsening heat treatment, which also spheroidizes eutectic tungsten to some extent, prior to cold working. The limited malleability of this alloy appears to be related to the heterogeneous distribution of nondeforming tungsten particles. Fracture surfaces of material that failed during drawing are populated heavily by such particles. The strengths of cold worked NW alloys of the present study exceed those of comparably deformed directionally solidified NiW eutectic alloys, at least up to deformation strains of 2.4. Since the latter type of alloy manifests extensive work hardening for deformation strains greater than 3.0, we expect this would also hold for the alloys described in this paper. Thus the NiW system, composed of a strong, tough nickel phase and a linear work hardening tungsten phase, is a likely candidate for development as a strong, tough, heavily deformed in situ composite.

The capillary shape instabilities associated with ribbon or finite plate dispersoids are described and documented with experimental evidence from three composite systems: (1) drawn castings of CuFe containing ribboned Fe fibers (14.3 vol.% Fe), (2) rolled liquid-phase sintered NiW alloys containing elliptic W plates (48 vol.% W), (3) rolled "hypoeutectic" NiW alloys containing W blades which occupy 17% of the eutectic microconstituent's volume. The primary instabilities observed include cylinderization via edge recession, boundary splitting via the thermal grooving of internal boundaries, and edge spheroidization via the ovulation of ridges formed by edge recession. For a given plate-shaped dispersoid, the dominant instability is determined by cross sectional aspect ratio (width/thickness) and, when internal boundaries are present, the ratio of the internal boundary's energy to that of the phase interface.

The tensile properties of brass (Cu-30% Zn)-nickel base metallic glass (MBF-35 Metglas) laminates have been investigated. Laminates were prepared by soldering these constituents together with a Pb-Sn alloy. The metallic glass exhibited an enhanced tensile ductility in the metal matrix environments, and such enhanced ductility depended on the metal matrix strength and elongation. Multiple shear bands have been observed in the metallic glass ribbon with enhanced tensile ductility. The failure modes of the laminates have been analysed based on stress-strain concentration concepts, following failure of the glass. The results were consistent with the experimental observations.

This paper discusses the potential of NiW alloys of differing initial microstructures, for high-strain cold deformation processing, and thus their suitability for development as heavily deformed, high strength in situ composites. Varying initial phase morphologies and tungsten volume fractions were produced by variations in initial processing. Liquid-phase sintered structures, containing 48 vol.% W, can be cold rolled to true strains of 2.4. They presumably could be cold worked further, but size limitations imposed by our processing capability prevented that being done in this study. Likewise, low volume fraction (of less than 15 vol.%) tungsten alloys, produced by casting of a hypoeutectic nickel-rich alloy and by transient liquid-phase sintering, can be cold rolled to the same strain as the liquid-phase sintered NiW structure. In contrast, as-cast arc melted alloys cannot be cold drawn to any extent at room temperature. They can be made capable of limited drawability by subjecting them to a coarsening heat treatment, which also spheroidizes eutectic tungsten to some extent, prior to cold working. The limited malleability of this alloy appears to be related to the heterogeneous distribution of nondeforming tungsten particles. Fracture surfaces of material that failed during drawing are populated heavily by such particles. The strengths of cold worked NW alloys of the present study exceed those of comparably deformed directionally solidified NiW eutectic alloys, at least up to deformation strains of 2.4. Since the latter type of alloy manifests extensive work hardening for deformation strains greater than 3.0, we expect this would also hold for the alloys described in this paper. Thus the NiW system, composed of a strong, tough nickel phase and a linear work hardening tungsten phase, is a likely candidate for development as a strong, tough, heavily deformed in situ composite.

The capillary shape instabilities associated with ribbon or finite plate dispersoids are described and documented with experimental evidence from three composite systems: (1) drawn castings of CuFe containing ribboned Fe fibers (14.3 vol.% Fe), (2) rolled liquid-phase sintered NiW alloys containing elliptic W plates (48 vol.% W), (3) rolled "hypoeutectic" NiW alloys containing W blades which occupy 17% of the eutectic microconstituent's volume. The primary instabilities observed include cylinderization via edge recession, boundary splitting via the thermal grooving of internal boundaries, and edge spheroidization via the ovulation of ridges formed by edge recession. For a given plate-shaped dispersoid, the dominant instability is determined by cross sectional aspect ratio (width/thickness) and, when internal boundaries are present, the ratio of the internal boundary's energy to that of the phase interface.

The tensile properties of brass (Cu-30% Zn)-nickel base metallic glass (MBF-35 Metglas) laminates have been investigated. Laminates were prepared by soldering these constituents together with a Pb-Sn alloy. The metallic glass exhibited an enhanced tensile ductility in the metal matrix environments, and such enhanced ductility depended on the metal matrix strength and elongation. Multiple shear bands have been observed in the metallic glass ribbon with enhanced tensile ductility. The failure modes of the laminates have been analysed based on stress-strain concentration concepts, following failure of the glass. The results were consistent with the experimental observations.

Tensile testing of high volume fraction tungsten-aluminum and molybdenum-aluminum composites has been carried out at temperatures ranging from 25 to -196 C and elongation rates of 0.002 and 0.1 in./min respectively. The effect of constant strain rate tensile tests on observed fracture modes was investigated theoretically. Stress-strain behavior was analyzed by fiber size, inter-fiber spacing, character of flows, temperature, strain-rate and condition of material. (P.S.-PL)