MECHANISM OF GRAIN REFINEMENT IN ALUMINIUM ALLOYS IN THE PROCESS OF HYDROSTATIC EXTRUSION

Malgorzata Lewandowska 

Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland

Abstract

Hydrostatic extrusion (HE) is one of the methods that enable relatively high strains. Its unique features are three-axial compressive stresses within the billet and high strain rates. This results in a rapid processing under high pressure and may provide a new opportunity for suppressing recovery and possible grain growth in heavily deformed materials. This work describes the microstructure evolutions and mechanisms of grain refinement in aluminium alloys processed by this deformation method.
The materials used in this study represent different series of aluminium alloys and include heat-treatable (2XXX and 7XXX series) and non heat-treatable (1XXX series) alloys. The microstructure observations were performed by using TEM and SEM techniques. Next, the revealed microstructures were described quantitatively in terms of the grain size and shape. The distributions of misorientations between neighbouring grains were also calculated on the basis of crystallographic orientations of the grains measured from Kikuchi lines obtained in TEM.
It has been found that the processing by HE results in a significant grain refinement and the formation of large fraction of deformation induced high angle grain boundaries (HAGBs). From the quantitative analysis of the material microstructure and grain boundary characteristics, the contribution of different mechanisms of grain refinement (e.g. continuous dynamic recrystallization, grain rotation) was analysed. These results were compared to aluminium alloys processed by other severe plastic deformation methods. Moreover, one of the aspects of microstructural analysis was the evolution of size, shape and distribution of second phase particles (precipitates and intermetallics). Their influence on the process of grain refinement and HAGB distribution was discussed.

 

Related papers
  1. Joining ultrafine grained aluminium by friction stir welding - processing, microstructure and mechanical properties
  2. Experimental evaluation of melting point depression in AlSi/AlN nanomultilayer system
  3. Nanotechnologie w gospodarce województwa podlaskiego
  4. (Cd, Mn)Te Crystals for X and Gamma Radiation Detectors - an Alternative Material to CdTe and (Cd,Zn)Te. 
  5. Industrial perspectives of nanometals
  6. SEM studies of the etched surface of (Cd,Mn)Te
  7. Welcome address
  8. Atomic force microscopy characterization of corneocytes
  9. TiO2 nanotubes based composite layers for biomedical applications
  10. Scale up of nanometals production
  11. Otwarcie konferencji
  12. Reduced activation ODS ferritic steel – recent development in high speed hot extrusion processing
  13. The influence of grain refinement on the corrosion mechanism of 7475 aluminium alloy
  14. Wear resistance of the nanostructured 316 LVM austenitic stainless steel processed by hydrostatic extrusion
  15. Recrystallization and Grain Growth in Nano-structured Austenitic Stainless Steel under Electric Current Heating
  16. Grain refinement in CuCrZr by SPD processing
  17. Tailoring mechanical properties of nano-structured Eurofer 97 steel for fusion applications
  18. Microscopic and surface analytical characterization of TiO2 nanotubes produced by anodic oxidation and thermal treatment 
  19. Ceramic-polymer composites for medical application
  20. Microstructural and mechanical characterization of zirconia based composite
  21. The influence of nanosilica on wear resistance of ceramic-polymer composites intended for dental fillings
  22. Tailoring mechanical properties by grain refinement and particle redistribution
  23. Nowe materiały metaliczne o strukturze nanometrycznej do zastosowań w nowoczesnych gałęziach gospodarki
  24. Recent Advances in Making Nanometals by Heavy Plastic Deformation
  25. Morphological and surface analytical characterization of chemically pretreated Ti surfaces intended for biomedical applications
  26. Microstructure and mechanical properties of 7475 aluminium alloy processed by SPD methods
  27. Investigation of aqueous surface processes and corrosion mechanisms of Al-(Cu)-Fe-Cr quasicrystaline approximant
  28. On some peculiarities of electrochemical oxidation of Ti and Ti6Al6V alloy
  29. Nanomaterials in dental applications
  30. Nanostructure formation in austenitic stainless steel
  31. Evaluation of crystal structure and polytypism of SiC in microwave sintered diamond-SiC composite by TEM and HR-TEM
  32. Stability of second phase particles during processing by hydrostatic extrusion
  33. The influence of nano - filler on microstructure homogeneity and selected properties of dental ceramic - polymer composites
  34. Structural stability of zirconia ceramic in water and acid solutions
  35. Morphology and chemical characterization of Ti surfaces modified for biomedical applications
  36. Evaluation of degradation degree of dental hybrid composite used as permanent fillings
  37. The influence of hydrostatic extrusion on mechanical properties and tribological characteristics of an austenitic stainless steel
  38. The Influence of hydrostatic extrusion on microstructure of 6082 aluminum alloy
  39. SEM investigations of tooth/ filling bonding
  40. Development of microstructure and mechanical properties in nickel deformed by hydrostatic extrusion
  41. Nanometals for medical applications
  42. The influence of twin bands density on microstructure of 316LVM austenitic stainless steel subjected to transverse rolling
  43. Microstructure evaluation in an Al-Li alloy processed by severe plastic deformation
  44. EFFECT OF INITIAL MICROSTRUCTURE ON MECHANICAL PROPERTIES OF THE Al-Cu-Mg-Mn ALLOY PROCESSED BY HYDROSTATIC EXTRUSION
  45. SHRINKAGE OF DENTAL POLYMERIC COMPOSITES
  46. Microstructure and mechanical properties of binary Al-Li alloys processed by ECAP
  47. Microstructure of the ceramic - polymer composites for dental applications
  48. Hydrostatic extrusion and nanostructure formation in an aluminium alloy

Presentation: oral at E-MRS Fall Meeting 2005, Symposium I, by Malgorzata Lewandowska
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-17 07:41
Revised:   2009-06-07 00:44