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  • 1
    Electronic Resource
    Electronic Resource
    Shear localization and chemical reaction in Ti–Si and Nb–Si powder mixtures: Thermochemical analysis (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3098-3106 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Chemical reactions in Ti–Si and Nb–Si powder mixtures were initiated in regions of high plastic strain induced by high-strain-rate deformation. These regions of high localized plastic strain had thicknesses of 10–25 μm and a characteristic spacing of 600–1000 μm. Scaling up of the experiments revealed a shear-band spacing that is constant and dictated by material and deformation parameters. The generation of heat due to plastic deformation and chemical reaction is treated in a one-dimensional calculation. The calculations are in qualitative agreement with experimental results: shear bands can serve as ignition regions for the propagation of the reaction throughout the entire specimen for Ti–Si, whereas in the Nb–Si system (that has a much lower enthalpy of reaction), the reaction is always localized in the shear bands. These results enable the estimation of a reaction time in the Ti–Si mixture (∼10 ms) and of a critical global strain required for the complete reaction to take place (εeff=0.38). This is a new regime of reaction, intermediate between combustion synthesis and shock compression synthesis. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368464
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  • 2
    Electronic Resource
    Electronic Resource
    Inhomogeneities of shock-wave deformation in Fe-32 wt. % Ni-0.035 wt. % C alloy (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2791-2794 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-pressure plane impact experiments performed on Fe-32 wt. % Ni-0.035 wt. % C alloy revealed, after recovery, markings which are attributed to shock-induced inhomogeneities. Shear of the material does not occur homogeneously, but in preferential planar regions. These regions are made visible by a martensitic transformation [fcc (austenite)→bcc (martensite)] produced by the tensile pulses generated by the reflection of the compressive shock wave at a free surface. The bands with higher plastic deformation served as preferential nucleation sites for martensitic transformation. The formation of these bands is attributed to inhomogeneous yielding due to work softening of the material during tensile loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335875
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  • 3
    Electronic Resource
    Electronic Resource
    Controlled high-rate localized shear in porous reactive media (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3069-3071 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is demonstrated that controlled high-strain-rate plastic deformation of heterogeneous reactive porous materials (Nb+Si, Mo+Si+MoSi2) produces shear localization. Within the shear bands, having thicknesses 5–20 μm, the overall strains (γ≤100) and strain rates (γ(overdot)≤107 s−1) result in changes in particle morphology, melting, and regions of partial reaction. The shear band thickness is smaller than the initial characteristic particle size of the porous mixture (≤44 μm). This ensures quenching of the deformed material structure in the same time scale as the deformation time (10−5 s). In the shear localization region, two types of patterning are observed: (a) a characteristic shear fracture which subdivides the Nb particles into thin parallel layers and (b) the formation of vortices. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112509
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  • 4
    Electronic Resource
    Electronic Resource
    Observations on the ferromagnetic β phase of the Cu–Mn–Sn system (1973)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 6 (1973), S. 39-41 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The copper-rich portion of the copper–manganese–tin system was investigated by X-ray diffraction, electron microprobe, and magnetometric techniques. A model for the ordering taking place in the β phase was established. Two low-temperature phases for the alloy composition Cu2MnSn were identified, and the existence of the intermetallic compound Cu4MnSn was confirmed. Another low-temperature phase was found; it is α or β manganese, and its appearance contradicts previous investigations. The saturation magnetizations were measured and correlated with a function of the long-range ordering in the β structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889873008022
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  • 5
    Electronic Resource
    Electronic Resource
    Shock synthesis and synthesis-assisted shock consolidation of suicides (1991)
    Springer
    Journal of materials science 26 (1991), S. 601-611 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Shock-induced chemical synthesis and synthesis-assisted consolidation of high-temperature materials (suicides) were investigated. Niobium, molybdenum, and titanium powders mixed with silicon powders were chosen as reactant materials for shock-induced synthesis of silicides. In parallel experiments, these reactant materials were also respectively mixed with inert intermetallic compound powders of NbSi2, MoSi2, and Ti5Si3 in different proportions and were shock consolidated. Shock processing was carried out using a modification of the experimental set-up developed by Sawaoka and Akashi. The shock waves were generated in the materials by the impact of a flyer plate at a velocity of 2 km sec−1. An explosive plane-wave generator was used to initiate the main explosive charge to accelerate the flyer plate. The passage of shock waves of sufficient pressure and temperature induced a highly exothermic and self-sustaining reaction between reactant materials. The shock-synthesized intermetallic compounds and the heat of reaction enhanced bonding between inert matrix materials. The proportion of reactant powder mixtures blended with inert intermetallic materials plays a very important role in the synthesis-assisted consolidation process. Characterization of compacts was done by optical microscopy, scanning electron microscopy, and X-ray diffraction. A preliminary analysis of shock-induced chemical reactions is conducted; it predicts a 30% increase in shock pressure and shock-wave velocity over those in unreacted powders. For shock synthesis, the profuse formation of voids indicates that melting of the material occurred; in contrast, unreacted regions did not exhibit porosity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588294
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic consolidation/hot isostatic pressing of SiC (1996)
    Springer
    Journal of materials science 31 (1996), S. 252-261 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Shock consolidation is a method that presents a bright potential but has been limited by inevitable cracking of compacts, especially for ceramics. In an effort to eliminate cracking while retaining the unique features of shock consolidation, three novel approaches have been implemented: (1) the use of local shock-induced reactions to increase the temperature of particle surfaces and to provide a bonding phase (reaction products); (2) shock densification at a low pressure (just above the threshold for pore collapse) followed by hot isostatic pressing; (3) shock consolidation of pre-heated specimens. These techniques were applied to silicon carbide. Reduction of cracking was observed with interparticle melting and reactions. Microstructural results, mechanical properties and advantages and limitations of these approaches are discussed. It is shown that shock consolidation of ceramics is inherently limited because shock-induced cracks are introduced into the process, damaging the particles. A criterion for the plastic deformation versus fracture of ceramic powders under shock consolidation is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00355153
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  • 7
    Electronic Resource
    Electronic Resource
    Warm shock consolidation of IN 718 powder (1988)
    Springer
    Journal of materials science 23 (1988), S. 1786-1804 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Explosive consolidation of the rapidly-solidified nickel-base super-alloy powder IN 718 was successfully accomplished. The effects of explosive type, explosive-to-powder mass ratio, powder container material and thickness, type of confinement, shielding material, and preheating temperature were investigated. Conditions for satisfactory consolidation, with good mechanical properties and low microcrack density, were established. The best consolidation was achieved by using a double-tube design in which a flyer tube was explosively accelerated, impacting the (cylindrical) powder container. The powder was pre-heated at 525° C and the initial consolidation pressure was calculated to be 18 GPa, resulting in approximately 20% apparent interparticle melting (white-etching regions between particles). The quality of the consolidates was evaluated by optical and electron microscopy, and by tensile testing.[/p]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01115723
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  • 8
    Electronic Resource
    Electronic Resource
    Dynamic consolidation of rapidly solidified titanium alloy powders by explosives (1991)
    Springer
    Journal of materials science 26 (1991), S. 1277-1286 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Consolidation of rapidly solidified titanium alloy powders employing explosively generated shock pressures was carried out successfully. The cylindrical explosive consolidation technique was utilized, and compacts with densities in the range 97 to 100% were produced. Better consolidation (with more interparticle melting regions and less cracking) was achieved by using a double tube design in which the outer tube (flyer tube) was explosively accelerated, impacting the powder container. Optical and transmission electron microscopy observations were carried out to establish microstructural properties of the products. It was observed that consolidation is achieved by interparticle melting occurring during the process. The interior of the particles in Ti-17 alloy exhibited planar arrays of dislocations and twin-like features characteristic of shock loading. Two dominant types of microstructures (lath and equiaxed) were observed both in Ti-662 and Ti-6242 + 1% Er compacts, and very fine erbia (Er2O3) particles were seen in the latter alloy. The micro-indentation hardness of the consolidated products was found to be higher than that of the as-received powder material; and the yield and ultimate tensile strengths were found to be approximately the same as in the as-cast and forged conditions. The ductilities (as measured by the total elongation) of the shockcompacted materials were much lower than those of the cast or forged alloys. Hot isostatic pressing of the shock-consolidated alloys increased their ductility. This enhancement in ductility is thought to be due to the closure of existing cracks. These excellent mechanical properties are a consequence of strong interparticle bonding between individual powder particles. It was also established that scaling up the powder compacts in size is possible and compacts with 50, 75, and 100 mm diameter were successfully produced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00544466
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  • 9
    Electronic Resource
    Electronic Resource
    Hot dynamic consolidation of hard ceramics (1992)
    Springer
    Journal of materials science 27 (1992), S. 5470-5476 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Diamond and cubic boron nitride powders were shock compacted at high temperature (873 and 973 K) by using a planar impact system at 1.2 and 2.0 km s−1. Silicon, graphite or a mixture of titanium and carbon powders were added to enhance the bonding of these superhard materials. Hot-consolidated specimens exhibited fewer surface cracks as compared with the specimens shock consolidated at room temperature. Diamond compacts having microhardness values over 55 GPa were obtained by subjecting porous mixtures of diamond crystals (4-8 μm) plus 15 wt% graphite (325 mesh) to an impact velocity of 1.2 km s−1 at 873 K. Well-consolidated c-BN samples, with microhardnesses (starting powders with 10–20 and 40–50 (μm) over 53 GPa were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541608
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  • 10
    Electronic Resource
    Electronic Resource
    h-BN ← w-BN phase transition under dynamic--static compression (1997)
    Springer
    Journal of materials science 16 (1997), S. 1625-1627 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018597224662
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