3.Induction (also known as polarization), which is the attractive interaction between a permanent multipole on one molecule with an induced multipole on another. 4.Dispersion , which is the attractive interaction between any pair of molecules, including non-polar atoms, arising from the interactions of instantaneous multipoles[2]. b. Chemical interaction: A chemical bond is an attraction between atoms or molecules and allows the formation of chemical compounds, which contain two or more atoms. A chemical bond is the attraction caused by the electromagnetic force between opposing charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of bonds varies considerably; there are "strong bonds" such as covalent and ionic bonds[3]. per forcec. Mechanical interaction: Stress is a measure of the average on which internal forces deformable body of a surface within a areaunit acting between forcesacts. It is a measure of the intensity of the internal particles of a deformable body across imaginary internal surfaces. These internal forces are produced between the particles in the body as a reaction to external forces applied on the body. External forces are either . Because the loaded deformable body is body forces or surface forces , these internal forces are distributed continuumassumed as a continuously within the volume of the material body, i.e., the stress distribution in the body is expressed as a piecewise continuous function (symbol pascal unit for stress is SIof space coordinates and time. The Pa), which is equivalent to one Newton (force) per square meter (unit area)[4] Many applications in industry, depends on dissimilar material joints. Due to the difference in chemical, mechanical and thermal behaviors of materials, the joining of dissimilar materials presents a challenges, significantly different than similar materials joining [1]. Bonding as a subdivision of both solid-state and liquid-phase welding, is a joining process wherein the principal mechanism is interdiffusion of atoms across the interface. The bonds is a result of chemical and/or physical interaction for the two faced materials prepared for joining. a. Physical interaction: Van der Waals forces include attractions between atoms, molecules, and surfaces. They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles (a consequence of quantum dynamics)[2]. Intermolecular forces have four major contributions: 1.A repulsive component resulting from the Pauli exclusion principle that prevents the collapse of molecules. 2.Attractive or repulsive electrostatic interactions between permanent charges (in the case of molecular ions), dipoles (in the case of molecules thout inversion center), quadrupoles (all molecules with symmetry lower than cubic), and in general between permanent multipoles 3.Induction (also known as polarization), which is the attractive interaction between a permanent multipole on one molecule with an induced multipole on another. 4.Dispersion , which is the attractive interaction between any pair of molecules, including non-polar atoms, arising from the interactions of instantaneous multipoles[2]. b. Chemical interaction: A chemical bond is an attraction between atoms or molecules and allows the formation of chemical compounds, which contain two or more atoms. A chemical bond is the attraction caused by the electromagnetic force between opposing charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of bonds varies considerably; there are "strong bonds" such as covalent and ionic bonds[3]. per forcec. Mechanical interaction: Stress is a measure of the average on which internal forces deformable body of a surface within a areaunit acting between forcesacts. It is a measure of the intensity of the internal particles of a deformable body across imaginary internal surfaces. These internal forces are produced between the particles in the body as a reaction to external forces applied on the body. External forces are either . Because the loaded deformable body is body forces or surface forces , these internal forces are distributed continuumassumed as a continuously within the volume of the material body, i.e., the stress distribution in the body is expressed as a piecewise continuous function (symbol pascal unit for stress is SIof space coordinates and time. The Pa), which is equivalent to one Newton (force) per square meter (unit area)[4]