Effects of aging on the microstructure of a Cu-Al-Ni-Mn shape memory alloy

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Abstract

The influence of aging on the microstructure and mechanical properties of Cu-11.6wt%Al-3.9wt%Ni-2.5wt%Mn shape memory alloy (SMA) was studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometer, and differential scanning calorimeter (DSC). Experimental results show that bainite, γ2, and α phase precipitates occur with the aging effect in the alloy. After aging at 300dgC, the bainitic precipitates appear at the early stages of aging, while the precipitates of γ2 phase are observed for a longer aging time. When the aging temperature increases, the bainite gradually evolves into γ2 phase and equilibrium α phase (bcc) precipitates from the remaining parent phase. Thus, the bainite, γ2, and α phases appear, while the martensite phase disappears progressively in the alloy. The bainitic precipitates decrease the reverse transformation temperature while the γ2 phase precipitates increase these temperatures with a decrease of solute content in the retained parent phase. On the other hand, these precipitations cause an increasing in hardness of the alloy.

Keywords

copper alloys shape memory effect martensitic transformations aging precipitates 
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© University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Department of Elementary Education, Elementary Science EducationKirikkale UniversityKirikkaleTurkey
  2. 2.Department of Computer Education and Instructional TechnologyKirikkale UniversityKirikkaleTurkey
  3. 3.Institute of SciencesKirikkale UniversityKirikkaleTurkey
  4. 4.Department of PhysicsKirikkale UniversityKirikkaleTurkey

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