Dissertation > Excellent graduate degree dissertation topics show

Effects of Processing Technology and Stacking Fault Energies on the Mechanical Properties of Cu-Al Alloys

Author: LongYan
Tutor: ZhuXinKun
School: Kunming University of Science and Technology
Course: Materials Physical Chemistry,
Keywords: copper alloy Ultra-fine crystal stacking fault energy MechanicalAnnealing hardening
CLC: TG146.11
Type: Master's thesis
Year: 2013
Downloads: 52
Quote: 0
Read: Download Dissertation

Abstract


With the continuous development of human society, people are now paying more attention to the performance of materials. So, it is very necessary to propose some feasible methods to improve the properties of the materials and increase the practical applications of the materials. Cu and Cu-Al alloy make great contributions to the social development, the properties of the Cu-Al alloy could be improved in various ways, such as solution strengthening, grain refinement strengthening, dislocation strengthening, annealing strengthening, etc.All the materials that were selected in experiment of this article use weight percentage, Cu、Cu-2.2wt.%Al、Cu-4.5wt.%Al、Cu-6.9wt.%Al, respectively. This article obtained the Cu and Cu-Al alloy which have high strength and high plasticity simultaneously by using various test methods, these methods include rolling at room temperature, rolling in liquid nitrogen, High Pressure Torsion (HPT), rolling after the Split Hopkinson Pressure Bars, annealing strengthening and the best mechanical properties of the Cu-Al alloy was selected. In order to research the effects of the factors which include the stacking fault energy, processing method, rolling temperature, strain rate and annealing temperature on mechanical properties of materials, we precede stretch experiment on a series of samples, and to analyze the relation of the micro structure and mechanical properties, we precede XRD test on part of test samples.By testing the mechanical properties of samples which are prepared in various processes, we found:with the increasing of Al, the stacking fault energy of the materials decrease, the strength and plasticity of the materials increased simultaneously, the yield strength increased from377.3MPa in Cu to759.8MPa in Cu-6.9wt.%Al, the breaking strength increased from395.6MPa in Cu to882.6MPa in Cu-6.9wt.%Al, and the uniform elongation increased from1.2%in Cu to2.3%in Cu-6.9wt.%Al. By observing the XRD results of rolling samples, we found:with the increasing of Al, the grain size of materials reduced gradually, while the microscopic stress, dislocation density and the twin-crystal density greatly increased.Tensile tests were carried out after the rolling samples annealing at 150℃,200℃,250℃for1h, respectively. We found:the samples which have a high stacking fault energy, such as Cu and Cu-2.2wt.%Al, tend to soften slightly after annealing. However, the samples which have a low stacking fault energy, such as Cu-4.5wt.%Al, Cu-6.9wt.%Al, have a obvious hardening phenomenon after annealing. What’s more, the hardening phenomenon of Cu-6.9wt.%Al was more obvious, in order to research the reason of the hardening phenomenon, we proceed XRD test on Cu-6.9wt.%Al and it’s annealed samples.Tensile tests were carried out on samples that were rolled after Split Hopkinson Press Bars (SHPB)(strain rateε=104S-1) and rolled at room temperature(strain rate ε=5S-1), the result showed:compared to the rolled samples, Cu, Cu-2.2wt.%Al that was rolled after Split Hopkinson Press Bars (SHPB), the strength and plasticity of the materials increased simultaneously. However, compared to the rolled samples, the strength of Cu-4.5wt.%Al and Cu-6.9wt.%Al increased obviously and the plasticity reduced slightly. By observing the XRD results of samples, we found:the grain size of the samples that were rolled after Split Hopkinson Press Bars (SHPB) reduced gradually, while the dislocation density and the twin-crystal density greatly increased.Tensile tests were carried out on samples that were rolled in liquid nitrogen and rolled at room temperature, the result showed:compared to the samples rolled at room temperature, the strength and plasticity of the materials that were rolled in liquid nitrogen increased obviously. By observing the XRD results of samples, we found:the grain size of the samples that were rolled in liquid nitrogen is smaller, while the microscopic stress, dislocation density and the twin-crystal density greatly increased.

Related Dissertations

  1. Determination of Phosphorus in Copper Alloy by ICP-AES,TG115.33
  2. The Generalized Planner Fault Energies of Al3Sc and Al3Mg, and the Effect of Rare-earth Elements on the Stacking Faults of Mg,TG146.22
  3. Effect of Stacking-fault Energy on the Mechanical Properties and Microstructure of Ultrafine-grain Cu and Cu-Zn Alloys,TG146.11
  4. Influence of Stacking Fault Energy on the Strength and Ductility of Cu and Cu Alloys,TG146.11
  5. Study of Microstructure and Mechanical Properties of High Manganese Steel with Nb,TG142.1
  6. Research on Microstructure and Property of TiB2/Cu and Brass Fabricated by Equal Channel Angular Pressing,TG379
  7. Nano-scale adhesive contact and crack propagation Quasicontinuum Research,O346.1
  8. Theoretical Study on Dislocations in the Rare Gas Solid,O772
  9. Cr-Zr-Cu copper alloy TIG welding and post-weld heat treatment on Joint Microstructure and Properties,TG441.8
  10. Study on the Microstructures and Properties of Slot Wedge Copper Alloys Used in Ultra Supercritical Generator Rotor,TG146.11
  11. A First-Principle Study of Stacking-Fault Energy Barriers in Metals and Alloys,TG111.2
  12. Effects of Surface Nanocrystallization Induced by High Energy Shot Peening on Pure Copper and Its Alloy,TB383.1
  13. Study on New Style Die Steel for Copper Alloy,TG249.2
  14. Investigation of 0Cr18Ni9 Stainless Steel Supersonic Fine Particles Bombaeding(SFPB) Surface Nanocrystallization’s Mechanism and Property,TB383.1
  15. Generalized Stacking Fault Energy Calculated from First Principles and Analysis of Local Approximation,O481
  16. The Skytrain use asynchronous traction motor dedicated copper alloy,TG146.1
  17. Cu-Cr alloy is heated mold continuous casting,TG249
  18. Conventional water stabilizer corrosion of copper alloy HSn70-1B study,TG174
  19. Studies on the Electrochemical Performance of the Tin-copper Alloys Negative Materials,TM912
  20. A Study on Production Processes and Properties of Copper Alloys with High Strength and High Conductivity,TG146.11
  21. The Research on the Heat Treatments and the Performances of the Elastic Cu10Ni15MnAlTi Alloy,TG113

CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Heavy non - ferrous metals and their alloys > Copper
© 2012 www.DissertationTopic.Net  Mobile