Investigation of effects of annealing temperature, pressure and external magnetic field on x-ray intensity ratios and valence electron structure of shape memory nanoalloys

This PhD thesis consist of four stages. In the first stage, the various compositions (TixNi1-x, x=0; 0,3; 0,4; 0,5; 0,6; 0,7; 1) of TiNi shape memory nanoalloys (SMNAs) has been produced by sintering technique at different compression pressures (370 MPa, 740 MPa and 1110 MPa) and different annealing temperatures (25; 125; 250; 375; 500; 625; 750; 875 and 1000°C). In the second stage, Kα and Kβ emission spectra of Ti, Ni pure nano metals and produced TiNi SMNAs were measured in two different experiment geometries (1st experiment geometry: the experiment geometry without magnetic field, 2nd experiment geometry: the experiment geometry in which magnetic field system established) by energy dispersive X-ray fluorescence (EDXRF) technique using a Si(Li) semiconductor solid-state detector in the same experiment conditions. The IKβ/IKα X-ray intensity ratios of investigated samples were calculated for all conditions using the results obtained of emission spectra. In the third stage, a program was developed in order to determine valence electron structures of SMNAs via X-ray intensity ratios by using multi-configuration Dirac-Fock (MCDF) calculations and results. For all states, valence electron structures of Ti, Ni pure nano metals and SMNAs were calculated by using this program. Changes in valence electron structures were evaluated in terms of delocalization and/or charge transfer phenomena. In the fourth stage, morphological evaluations were performed by taking SEM images for investigated samples. For the annealing temperature effect on X-ray intensity ratios and valence electron structures of SMNAs; in the 1st experiment geometry, results obtained for all temperatures under compression pressure of 1110 MPa, for pressure effect; in the 1st experiment geometry, results obtained for all compression pressures at 1000°C annealing temperature, and for external magnetic field effect; in the 2nd experiment geometry, results obtained for external magnetic field of 0, 4000, 8000 Gauss under 1110 MPa compression pressure and at 1000°C annealing temperature were used and it was determined that these physical parameters and alloy concentrations have significant effect separately.