Investigation of Ni2MnAl-based shape memory alloys

In this thesis, crystallographic, magnetic and elastic properties of Ni2MnAl based shape memory alloys have been investigated.

Crystallographic investigations of the completely disordered Ni2Mn1.2Alo.8 have been carried out using neutron diffraction. The structure of the high temperature phase has been determined. A tool for approaching solutions of triclinic unit cell symmetries has been developed and applied on the experimental results of the low temperature phase. The analysis suggests structural contributions of monoclinic symmetry.

Magnetic properties of completely disordered Ni2MnxAl2_x for x = 1.0, 1.1, ..., 1.4 have been investigated at temperatures of 5K < T < 350K and magnetic fields up to 5T.

Strain-stress measurements have been carried out on Ni2Mni.2Al0.8- Young’s modulus has been determined for the temperatures T — 25°C, 75°C and 125°C.