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E u r o s c i c o n C o n f e r e n c e o n
Physical Chemistry and
Analytical Separation Techniques
October 08-09 , 2018
Amsterdam, Nether l ands
Journal of Organic & Inorganic Chemistry
ISSN: 2472-1123
Physical Chemistry and Analytical Separation Techniques 2018
S
hape memory effect is a peculiar property exhibited by series alloy systems in the β-phase fields. Successive martensitic
transformations, thermal induced and stress induced martensitic transformations govern shape memory effect in shape
memory alloys. Shape memory effect is performed thermally in a temperature interval on heating and cooling after deformation
in low temperature phase condition. Thermal and stressing processes govern shape memory effect in physical basis; twinning
and detwinning processes govern in crystallographic basis. Thermal induced martensitic transformation occurs as Martensite
variants with lattice twinning in crystallographic scale. Twinned Martensite structures turn into detwinned Martensite structure
by means of stress induced transformation Martensite variants occur with the cooperative movement of atoms by means of
shear-like mechanism. Copper based alloys exhibit this property in metastable β-phase region, which has bcc-based structures
at high temperature parent phase field and these structures martensitically turn into the complex stacking ordered structures
with lattice twinning reaction on cooling. Lattice invariant shears are not uniform in copper based shape memory alloys and
the ordered parent phase structures martensitically undergo the non-conventional complex layered structures on cooling. The
long-period layered structures can be described by different unit cells as 3R, 9R or 18R depending on the stacking sequences on
the close-packed planes of the ordered lattice. The close-packed planes, basal planes, exhibit high symmetry and short range
order as parent phase. The unit cell and periodicity is completed through 18 layers in direction z, in case of 18R Martensite, and
unit cells are not periodic in short range in direction z. In the present contribution, X-ray diffraction and transmission electron
microscope studies were carried out on two copper based CuZnAl and CuAlMn alloys. These alloy samples have been heat
treated for homogenization in the β-phase fields. X-ray diffraction profiles and electron diffraction patterns reveal that both alloys
exhibit super lattice reflections inherited from parent phase due to the displacive character of martensitic transformation. X-ray
diffractograms taken in a long time interval show that diffraction angles and intensities of diffraction peaks change with the aging
time at room temperature. In particular, some of the successive peak pairs providing a special relation between Miller indices
come close each other and this result leads to the rearrangement of atoms in diffusive manner.
oadiguzel@firat.edu.trO Adiguzel
Firat University, Turkey
J Org Inorg Chem 2018 Volume: 4
DOI: 10.21767/2472-1123-C6-018
Physical aspects and nanoscale
characterization of phase transformations in
shape memory alloys