Physics of the Effect of High-Temperature Pulse Heating On Defects in the Surface Layer of a Metal Alloy

Physical Mechanism of Nanocrystalline Composite Deformation Responsible for Fracture Plastic Nature at Cryogenic Temperatures

“…The heat transfer by the mechanism of thermal conductivity with internal heat sources in the investigated solid material is described by the differential equation of thermal conductivity (Fourier differential equation). Free convection occurs on the outer surface of the sample (except for the crack surface), which is described by the Newton–Richman Equation (5) [ 41 ]: where [W/m 2 ] is the heat flux density, [K] is the surface temperature of a solid, [K] is the ambient temperature, and [W/(m 2 K)] is the heat transfer coefficient by convection.…”

“…Since according to the results of preliminary model experiments the excess temperature does not have time to spread to the surface of the sample, it is true that , and then . Then, the boundary conditions of the third kind (Newton’s conditions) degenerate into boundary conditions of the second kind (Neumann’s conditions), and are used in further modeling [ 41 , 42 , 43 ]. The validity of the application of these boundary conditions is also confirmed by the fact that no heating of these surfaces was detected during the experiment.…”

“…Taking into account the kinematic/dynamic viscosity of nitrogen and the curved trajectory, we find that no convection cooling is observed at the crack tip during a time of the order of s on the crack surface. Thus, it is possible to proceed to the consideration of the thermal conductivity equation in view of meeting the criteria of the physical model discussed above [ 40 , 41 , 42 , 43 ]. Heat transfer by the mechanism of thermal conductivity in a solid material with internal heat sources is described by the differential equation of thermal conductivity (6): where is the selected area at the crack tip (see Figure 4 ), is the temperature (K), is the coefficient of specific thermal conductivity (W/(m 2 ·K)), is the specific heat capacity (J/(kg·K)), is the density (kg/m 3 ), and is the thermal power of internal heat sources (J/(s·m 3 )).…”

“…In this investigation, (using the finite element method), the original complex structure was (broken down) split into simple elements using the finite element method. Then, a system of algebraic equations was compiled based on the grid of the finite element method and the equation of thermal conductivity [ 40 , 41 , 42 , 43 ]. This system of equations was solved using a standard algorithm.…”

“…The heat transfer by the mechanism of thermal conductivity with internal heat sources in the investigated solid material is described by the differential equation of thermal conductivity (Fourier differential equation). Free convection occurs on the outer surface of the sample (except for the crack surface), which is described by the Newton-Richman Equation ( 5) [41]:…”