Numerical Study on the Bombardment Effects of Tungsten by High-Intensity Pulsed Ion Beam

Abstract

In order to study the response of tungsten under high heat load, the nonlinear thermodynamic equations considering the phase transition were established to the tungsten target irradiated by intense pulsed ion beam. Also the equations which describe the thermal stress and the total strain produced by the changed temperature in the material element were built. Numerical method was used to solve the evolutions of the thermal stress field formed in the target, and spatial temporal evolutions of stress field in the tungsten target are obtained. While the ion current density reached 100A/cm2, the surface materials of tungsten target at the beam incident center was melted and then re-solidified due to the heat conduction after the end of a pulse. There exists the gradient of temperature in tungsten, therefore the thermal stress formed. Radial tensile stress is produced within the melting region, meanwhile outside the region compressive stress is formed; the boundary appears on the edge of the melting region. The stresses on the incidental surface of target are larger compared with the internal.

Formation of Nano-Sized Structural-Phase States in Surface Layers of a Cermet Alloy and the Influence of the States on the Tool Life of Cermet Plates in Metal Cutting

“…Practical implementation of this approach consists in ensuring synchronization conditions for the following three independent processes: (1) ultra-fast heating of the surface layer to a very high temperature with partial dissolution of ceramic particles in the metal binder followed by ultra-fast quenching of the material; (2) micro-doping of the metal component of the cermet composition with ceramic-component elements; and (3) formation of a subsystem of nano-sized ceramic particles in the inter-particle layers of the metal component. The formation of a multi-level (in nano-scale size region) structural-phase state of the material in its surface layer leads to the formation of a highstrength multi-scale structure in which the determining contribution to the improvement of the physical and strength properties of surface layers is due to the nano-sized structural-phase states [1,2]. A highly efficient method for the mentioned modification of the structural-phase state in surface layers of a cermet alloy is offered by the treatment of alloy surfaces with a low-energy, highintensity electron beam of sub-millisecond duration [3,4].…”