**1. Introduction**

Intense development of science and technology with ever-increasing needs in new materials with the unique properties requires implementation of careful research in this area. Develop‐ ment and production of new types of materials is always related to the enormous costs and solving new technical problems of analytical and experimental nature. Recently a large class of the model alloys on metallic base, which meets various demands, has been created. A special place among them is occupied by the metals and alloys that undergo phase transformations. The requirements for the radiation resistance of these materials are of extraordinary impor‐ tance. Investigation of the fundamental properties of materials that determine their physical, chemical, mechanical, technological, operational and other characteristics enables one to establish a field of their rational application with maximal efficiency.

The attention of the researchers should be drawn to investigation of the structure transforma‐ tions in crystals, especially, their electronic and defect structure as well as their role in the process of formation of the material's final physical properties. Almost all of the material's properties are related to its electronic structure, and the constancy of the structure under external exposure determines stability of the main characteristics and can serve as a principal indicator of materials radiation resistance.

The problems of nuclear and thermonuclear power pose an urgent demand on continuous and wide range investigation of interaction processes of nuclear radiation with metallic materials, along with subsequent modification of their structure. For authentic establishing of common regularities of the observed phenomena, deep understanding of the processes of nucleation, formation and subsequent evolution and modification of the metals and alloys defect structure is crucial.

© 2013 Mukashev and Umarov; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Mukashev and Umarov; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In spite of considerable amount of realized investigations, the analysis of the obtained results justifies the following findings: by the time of preparation of this work, the lack of the systematic information was experienced about the character of the radiation damageability of some perspective constructional refractory metals and their alloys, which firstly undergo polymorphous or phase transformations; influence of the type and concentration of alloying elements on the character of the structural disturbances at plastic deformation and radiation exposure in conditions of vacancy and vacancy-impurity complexes formation, packing defects, dislocation loops subject to material history, fluence, energy, flux, nature of ionizing radiation, temperature of irradiation and postradiational annealing.

dence. 22Na nuclear decay occurs by the following scheme: 11 *<sup>N</sup>*<sup>22</sup> *<sup>a</sup>*→<sup>10</sup> *<sup>N</sup>*<sup>22</sup> *<sup>e</sup>* <sup>+</sup> *<sup>e</sup>* <sup>+</sup> <sup>+</sup> *γЯ*. In this nuclear decay reaction the 22Nа nuclear is produced in an excited state with the time of life less than 10-12 s. At the return to the ground state it emits the nuclear quantum with energy *Е*=1.28

Physicochemical and Radiation Modification of Titanium Alloys Structure

http://dx.doi.org/10.5772/55485

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The essence of using positrons for solid structure probing is explained in the following. A positron emitted by a source while penetrating in solid to a certain depth subject to energy, experiences numerous collisions with the atoms of the solid, and consequently this positron gradually loses its velocity and at the end gains energy that corresponds to environment's absolute temperature: *E*0 = *kT*=0.025 eV, where *k* is the Boltzmann constant. This process is referred to as the positron thermolysis. The fundamental result of this phenomenon is the positron thermalization time, during which the positron dissipates its initial energy. Its

Positron thermolysis process occurs during the time, which is considerably shorter than its life time before annihilation. This circumstance serves as grounds for using positrons in order to study the properties of condensed matters, because the conduction electrons, with which positron interacts, occupy the energetic band of the range of several electron-volt and more importantly positron does not contribute to the total pulse and energy of the pair and hence can be neglected. Therefore, the information, which is carried by the positron annihilation photons, corresponds to solid electrons state, in which positron's thermolysis and interaction

Annihilation is the act of mutual destruction of a particle and its appropriate antiparticle. While no absolute destruction of either matter or energy occurs, instead there is a mutual transfor‐

Due to the law of charge parity a positron in singlet state (1S0) decays with emission of even number (usually two) gamma-ray quanta. A positron in triplet state annihilates with emission of odd number (usually three) photons. The probability of the 3γ - process is lower by more than two orders than the probability of the 2γ - process. Therefore, all basic research that is oriented towards studying properties of condensed state properties is performed around this

If an annihilation pair is found in the state of rest in center-of-mass system (v=0), then in laboratory system of coordinates two photons would be emitted strictly in opposite directions at sin*θ* =0 (Fig.1a). As a result of interaction with the medium's electrons and phonons, positron completely thermalizes and in essence is in state of rest. However, we cannot state the same about electron, the other immediate participant of the annihilation process. At the same time

pulse transverse component leads to deflection of γ1 and γ2 photons from collinearity:

<sup>0</sup> ; *Z z P mc* = q

This circumstance is initiating development of the method of measuring angular distribution of annihilatedphotons(ADAP).Thepurposeofthemethodistoobtaininformationaboutelectrons

(1)

mation of particles and energy transitions from one form to another.

MeV, which effectively testifies positron production.

calculated value is 3 10-12 s. [1].

phenomenon.

and annihilation processes have occurred.

There was no a thorough research of the influence of preliminary thermochemical treatment, includinghydrogenandotheratomicgasessaturationandcyclicthermalshockswithanaccount of reconstruction of electron structure and density of pulse distribution of electrons in the field of defect production on the materials' final properties. Availability of such data would com‐ plete a full picture of purposeful properties changes and make possible working the materials with predetermined properties. This problem definition caused by demands of the state-of-theart science and technology appears to be strategically important area of research in the fields of physics of metals, physics of radiation damage and radiative study of materials.

Therefore, the main goal of the present work, which is based on the authors' own research, is investigation and establishment of regularities of the electron structure alteration and its correlation with different titanium alloys crystal lattice defects created as a result of deforma‐ tion radiation and complex thermochemical treatment.
