scholarly journals Influence of deformation degree at cold-rolling on the anneal hardening effect in sintered copper-based alloys

2004 ◽  
Vol 40 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Svetlana Nestorovic
Keyword(s):  
Cold Rolling ◽  
Annealing Temperature ◽  
Pure Copper ◽  
Deformation Degree ◽  
Temperature Range ◽  
Hardening Effect ◽  
Sintered Copper ◽  
Anneal Hardening

Samples of copper-based alloys, Cu-4at%Zn, Cu-8at%Zn and Cu-5at%Ni-2at%Sn and pure copper have been prepared by a powder metallurgical method. The samples were subjected to cold rolling to 30, 50 and 70% in reduction, followed by annealing up to the recrystallization temperatures. Anneal hardening effect has been observed with the alloys in an annealing temperature range of 180-4000C, the hardness being increased with the amount of reduction at the prior cold - rolling.

scholarly journals Anneal hardening effect in sintered copper alloys

2002 ◽  
Vol 34 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Svetlana Nestorovic ◽  
Boran Milicevic ◽  
Desimir Markovic
Keyword(s):  
Electrical Conductivity ◽  
Cold Rolling ◽  
Copper Alloys ◽  
Recrystallization Temperature ◽  
Temperature Range ◽  
Hardening Effect ◽  
Sintered Copper ◽  
Anneal Hardening ◽  
Cold Rolled

Samples of copper and copper alloys CuNi and CuNiAl were prepared by a powder metallurgical method and were then subjected to cold rolling with different degrees of deformation. Copper and copper alloys in the cold-rolled state were isochronally annealed up to the recrystallization temperature during which hardness and electrical conductivity were measured. This investigation shows that the anneal hardening effect occurs in a temperature range of 450 - 650 K, followed with an increase in hardness of alloys.

scholarly journals Correlation between mechanical properties and structural changes of the sintered Cu-4 at% Ag alloy during thermomechanical treatment

2008 ◽  
Vol 62 (2) ◽  
pp. 78-84
Author(s):  
Ivana Rangelov ◽  
Svetlana Nestorovic ◽  
Desimir Markovic
Keyword(s):  
Mechanical Properties ◽  
Cold Rolling ◽  
Thermomechanical Treatment ◽  
Structural Changes ◽  
Solute Segregation ◽  
Recrystallization Temperature ◽  
Micro Structure ◽  
Deformation Degree ◽  
Sintered Copper ◽  
Anneal Hardening

Influence of thermomechanical treatment on micro structure and strength (hardness and microhardness) of the sintered copper based Cu-4 at% Ag alloy was investigated using Vickers hardness and microhardness measurements, and optical microscopy. After sintering at 790?C, samples of Cu-4 at% Ag alloy were subjected to thermomechanical treatment by cold rolling with 20, 40 and 60% deformation degrees, and annealing below and over the recrystallization temperature. It was shown that microstructure of Cu-4 at% Ag alloy changed with thermomechanical treatment, which directly causes changes of mechanical properties. Optical microphotograph of the sintered Cu-4 at% Ag alloy shows relatively homogeneous structure with spherical pores presented. The strength (hardness and microhardness) of the sintered Cu-4 at% Ag alloy during cold rolling increases with deformation degree due to deformation strengthening. Maximum values of hardness and microhardness were for 60% deformation. The porosity still exists in spite of the fact that compacting was carried out during the cold rolling. The hardness and microhardness continue to increase after annealing at temperature bellow recrystallization temperature due to anneal hardening effect which occurs in a temperature range of 160-350?C. It was concluded that solute segregation to dislocations, analogous to the formation of Cottrel atmosphere in interstitial solid solutions, is primarily responsible for anneal hardening phenomenon. Annealing at higher temperatures (higher than 400?C) results in strength decrease due to beginning of alloy recrystallization.

scholarly journals Influence of time of annealing on anneal hardening effect of a cast CuZn alloy

2003 ◽  
Vol 39 (3-4) ◽  
pp. 489-497 ◽  
Author(s):  
Svetlana Nestorovic ◽  
Lj. Ivanic ◽  
Desimir Markovic
Keyword(s):  
Copper Alloy ◽  
Cold Work ◽  
Pure Copper ◽  
Lattice Parameter ◽  
Recrystallization Temperature ◽  
X Ray ◽  
Hardening Effect ◽  
Anneal Hardening ◽  
Cold Rolled ◽  
Cuzn Alloy

Investigated cast copper alloy containing 8at%Zn of a solute. For comparison parallel specimens made from cast pure copper. Copper and copper alloy were subjected to cold rolling with different a final reduction of 30,50 and 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to recrystallization temperature. After that the values of hardness, strength and electrical conductivity were measured and X-ray analysis was performed. These investigations show that anneal hardening effect at alloys was attained under recrystallization temperature in the temperature range of 180-3000C, followed with an increase in hardness. The amount of strengthening increase with increasing degree of prior cold work. Also the X-ray analysis show the change of lattice parameter during annealing when anneal hardening effect was attained.

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

2018 ◽  
Vol 924 ◽  
pp. 333-338 ◽  
Author(s):  
Roberta Nipoti ◽  
Alberto Carnera ◽  
Giovanni Alfieri ◽  
Lukas Kranz
Keyword(s):  
Activation Energy ◽  
Sheet Resistance ◽  
Annealing Time ◽  
Thermal Activation ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Activation Energy ◽  
Electrical Activation ◽  
Temperature Range ◽  
Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

An anomaly in the specific heat below 3 °K of copper containing hydrogen

1969 ◽  
Vol 47 (14) ◽  
pp. 1485-1491 ◽  
Author(s):  
Neil Waterhouse
Keyword(s):  
Specific Heat ◽  
Molecular Hydrogen ◽  
Pure Copper ◽  
Solid Hydrogen ◽  
Rotational State ◽  
Experimental Results ◽  
Ortho Hydrogen ◽  
Temperature Range ◽  
A Value ◽  
Heat Curve

The specific heat of copper heated in hydrogen at 1040 °C has been measured over the temperature range 0.4 to 3.0 °K and found to be anomalous. The anomaly occurs in the same temperature range as the solid hydrogen λ anomaly which, in conjunction with evidence of ortho to para conversion of hydrogen in the sample, suggests the presence of molecular hydrogen in the copper. The anomaly reported by Martin for "as-received" American Smelting and Refining Company (ASARCO) 99.999+ % pure copper has been briefly compared with the present results. The form of the anomaly produced by the copper-hydrogen specimen has been compared with Schottky curves using the simplest possible model, that for two level splitting of the degenerate J = 1 rotational state of the ortho-hydrogen molecule.Maintenance of the copper-hydrogen sample at ~20 °K for approximately 1 week removed the "hump" in the specific heat curve. An equation of the form Cp = γT + (464.34/(θ0c)3)T3 was found to fit these experimental results and produced a value for γ which had increased over that for vacuumannealed pure copper by ~2%.

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