Inhomogeneous structure of near-surface layers in the ion-implanted NiTi alloy

This paper reports the application of nitrogen ion implantation for modification of a shape memory alloy. It is known that the problem of creating a protective surface coating for the shape memory alloy is the most acute for potential applications of this material. Thus, the problem of increasing surface protective properties and, at the same time, simultaneous preservation of functional properties of shape memory materials is a subject of research and development [Pelletier H, Muller D, Mille P, Grob J. Surf Coat Technol 2002;158:309.]. The surface characterization of nitrogen implanted (fluence 10¹⁸ cm^?2 and energy 50 keV) equiatomic commercial NiTi alloy samples was performed with the assistance of high resolution transmission electron microscopy (HTEM) techniques and modifications of phase composition before and after irradiation are studied at room and martensitic transformation temperatures by X-ray diffraction methods. Differential scanning calorimetry (DSC, TA Instruments) was used to characterize the transformation sequence and transformation temperatures for the initial and surface-modified materials. Experimental results of an inhomogeneous structure of near-surface layers in the ion-implanted NiTi alloy are discussed in this paper.     

Properties and structural-phase state of the surface layers of titanium after combined nitriding

We study the simultaneous nitriding of titanium alloys by two methods: thermodiffusion saturation and ion implantation. Prior to nitrogen implantation, a thin oxynitride film and a thick nitride one were formed on the surface of VT6 titanium alloy of the (α + β)-class (Ti-6Al-4V). We show that nitrogen implantation changes the state of the surface of titanium and increases the surface microhardness of nitride and oxynitride coatings. An increase in the hardness of the surface without loss of its quality is possible in the case of nitrogen implantation into a thin oxynitride film. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 3, pp. 65–70, May–June, 2007.     

Acoustic emission estimation of crack formation in aluminium alloys

In the paper a problem on the radiation of waves of acoustic emission (АЕ) during formation of penny-shaped crack in aluminium alloy elastic body under tensile and twisting loading is considered. By the method of integral transforms, the problem is reduced to the solving of Fredholm integral equation of the second kind. The dependences of component of displacement vector on time and distance to the viewpoint as well as amplitudes of the АЕ signals on the area of the crack and its spatial orientation are obtained.     

Wavelet analysis of Fourier polarized images of the human bile

The model of generalized optical anisotropy of human bile is suggested, and the method of the polarimetric phase Fourier transform of the image of the laser radiation field that is generated by the mechanisms of linear and circular birefringence of polycrystalline networks with a wavelet-diagnosis of cholelithiasis is analytically substantiated.