Manufacturing of dies from hardened tool steels by 3-axis micromilling

In this paper the results of an experimental investigation to analyze the machinability of a hardened, carbide-rich cold-work tool steel 1.2379 (approx. 62 HRC) with coated micro end-milling cutters are discussed. Fundamental experiments were performed to determine a cutting-parameter set, which enables an economic manufacturing of dies by 3-axis micromilling with commercially available cemented-carbide tools. The evaluation of the applicability of different tool types is conducted by analyzing the process forces, the tool wear, the surface quality, the material removal rate, and the entire chip volume. Design of experiments was used to significantly reduce the number of experiments and to model the active and passive forces. Concerning the design of tools for the micromilling of such difficult-to-machine materials, it is shown that cemented-carbide tools with robust cutting edges are applicable for this kind of machining. Furthermore, test microstructures were manufactured with the intention of validating the determined cutting-parameter set in combination with the selected tool types. In addition, the dimension and shape accuracy of the microstructures are analyzed.     

Semi conducting properties amd microstructure of x%V2O5·(100−x)% (As2O3·B203) glasses

Binary semiconducting glasses of the x%V₂O₅·(100?x)%(As₂O₃· B₂O₃) system with x ranging from 50 to 70 mol% have been investigated to elucidate their electronic conduction and microstructure. The values of conductivity and activation energy obtained for these glasses are in agreement with previous results on most V₂O₅-based glasses. Arguments for a small-polaron conduction of nonadiabatic type are presented. All the samples show a glass-glass type phase separation.     

Numerical Study on Magnetic Transitions in Double-Layer Spin Lattice Using Anisotropic Heisenberg Model

Monte Carlo simulations have been used to study the magnetic properties of double-layer thin film in Anisotropic Heisenberg Model with different anisotropy and direct exchange parameters, applying Metropolis algorithm. We investigate the antiferromagnetic ordering of the basal layer spins’ influence on the magnetic behavior of the superior layer. The magnetization, out-of-plane and in-plane magnetic susceptibilities, staggered magnetization and also the specific heat behaviors according to temperature are investigated in order to find out the potential magnetic ordered phases and the critical temperatures, for different parameter settings. Taking into account the balance between direct exchange and anisotropy interaction parameters we detect five different magnetic ordering states. These are: ferromagnetism, short-range ferromagnetism, antiferromagnetism, in-plane ordering and paramagnetism, which are characterized by specific properties; and we point also out some different magnetic phase transitions that can appear in the system.