Theoretical investigation of the process of cold extrusion of rods from unplasticized metal powders. I. Distribution of porosity and stresses in the conical seat of plastic deformation

1987 ◽  
Vol 26 (5) ◽  
pp. 353-356
Author(s):  
A. V. Stepanenko ◽  
L. A. Isaevich ◽  
A. A. Veremeichik ◽  
T. A. Medvedeva
Keyword(s):  
Plastic Deformation ◽  
Theoretical Investigation ◽  
Cold Extrusion ◽  
Metal Powders

scholarly journals Copper-Tantalum Metal Matrix Composites Consolidated from Powder Blends by Severe Plastic Deformation

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1010
Author(s):  
Zachary S. Levin ◽  
Michael J. Demkowicz ◽  
Karl T. Hartwig
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Equal Channel Angular Extrusion ◽  
Rate Sensitivity ◽  
Matrix Composites ◽  
Metal Powders ◽  
Tantalum Metal ◽  
Mechanical Bonding

We investigated the effectiveness of severe plastic deformation by equal channel angular extrusion (ECAE) for consolidation of metal powders into metal matrix composites. Equal volumes of copper (Cu) and tantalum (Ta) powders were consolidated at ambient temperature via different ECAE routes. Composites processed by ECAE routes 4E and 4Bc were also processed at 300 °C. The resulting materials were characterized by scanning electron microscopy (SEM) and compression testing. Processing by route 4Bc at 300 °C resulted in the highest compressive strength, lowest anisotropy, and least strain rate sensitivity. We conclude that the superior properties achieved by this route arise from mechanical bonding due to interlocking Cu and Ta phases as well as enhanced metallurgical bonds from contact of pristine metal surfaces when the material is sheared along orthogonal planes.

scholarly journals Micro Feature Enhanced Sinter Bonding of Metal Injection Molded (MIM) Parts to Solid Substrate

2011 ◽  
Author(s):  
Thomas Martens ◽  
Laine Mears
Keyword(s):  
Plastic Deformation ◽  
Solid Substrate ◽  
Full Density ◽  
Metal Powders ◽  
Solid Substrates ◽  
Injection Molded ◽  
Bond Strengths ◽  
Sinter Bonding ◽  
Micro Features ◽  
Plastic Injection

In MIM, fine metal powders are mixed with a binder and injected into molds, similar to plastic injection molding. After molding, the binder is removed from the part, and the compact is sintered to almost full density. The obstacle to sinter bonding a MIM part to a conventional (solid) substrate lies in the sinter shrinkage of the MIM part, which can be up to 20%, meaning that the MIM part shrinks during sintering, while the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. A structure of micro features molded onto the surface of the MIM part allows for shrinkage while bonding to the substrate. The micro features tolerate certain plastic deformation to permit the shrinkage without causing cracks after the initial bonds are established. In a first series of tests, bond strengths of up to 80% of that of resistance welds have been achieved. This paper describes how the authors developed their proposed method of sinter bonding and how they accomplished effective sinter bonds between MIM parts and solid substrates.

scholarly journals Theoretical Investigation of Ψ-Splitting After Plastic Deformation of Two-Phase Materials

1991 ◽  
Vol 14 ◽  
pp. 151-156 ◽  
Author(s):  
M. Berveiller ◽  
J. Krier ◽  
H. Ruppersberg ◽  
C. N. J. Wagner
Keyword(s):  
Plastic Deformation ◽  
Theoretical Investigation ◽  
Two Phase

Minimum Grain Size in Nanocrystalline Metal Powders

1992 ◽  
Vol 272 ◽  
Author(s):  
J. Eckert ◽  
Y. R. Abe ◽  
Z. Fu ◽  
W. L. Johnson
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Lower Bound ◽  
Ball Milling ◽  
Solid Solutions ◽  
General Relation ◽  
Metal Powders ◽  
Nanocrystalline Metal ◽  
Mechanical Attrition ◽  
Pure Metals

ABSTRACTNanocrystalline metal powders can be synthesized by mechanical attrition in a highenergy ball mill. A general relation determining the grain size of these materials is inferred. The ultimate grain size of nanocrystalline metals (typically 6 − 22 nm) is governed by the competition between the severe plastic deformation introduced during ball milling and the recovery behavior of the material. The lower bound grain size achievable by mechanical attrition is given by the minimum distance between two dislocations in a pile-up within a grain for all pure metals. Foar binary alloys the ultimate grain size depends on the composition of the material. Varying the composition changes the grain size reversibly. This can be explained by introducing solid solution hardening effects in the general relation for the lower bound grain size in pure metals. Thus, the proposed model for the ultimate grain size achievable by ball milling seems to be. applicable to all metals and alloys subjected to heavy mechanical deformation. However, reversible grain size changes are not restricted to mechanical attrition, but have also been observed for nanocrystalline Pd-H solid solutions produced by hydriding at constant pressure. Solid solutions prepared at different compositions, i.e. samples with different compositions, exhibit different grain sizes. Cycling between different temperatures/compositions changes the grain size reversibly. This cannot be explained by a model based on plastic deformation as in the case of ball-milled metal powders. The results are compared with data for ball-milled powders and samples prepared by inert gas condensation. The grain size changes are discussed with respect to the compositional changes and the grain boundary energy of the material.

Calculation of the process of cold extrusion of tubes from metal powders. II. Reverse extrusion

1989 ◽  
Vol 28 (5) ◽  
pp. 355-358
Author(s):  
A. V. Stepanenko ◽  
L. A. Isaevich ◽  
A. A. Veremeichik
Keyword(s):  
Cold Extrusion ◽  
Metal Powders

Calculation of the process of cold extrusion of tubes from metal powders. I. Direct extrusion

1989 ◽  
Vol 28 (3) ◽  
pp. 160-163
Author(s):  
A. V. Stepanenko ◽  
L. A. Isaevich ◽  
A. A. Veremeichik
Keyword(s):  
Cold Extrusion ◽  
Metal Powders ◽  
Direct Extrusion
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