Sharif Digital Repository

In current studies, equal channel angular pressing process (ECAP) and modified ECAP processes are simulated under ideal conditions to compare the deformation characteristics. The deformation behaviour is more complicated and the strain induced during the processes is highly non-uniform in the modified ECAP processes except in the equal channel multi-angular pressing (ECMAP) process with Route C. The strain homogeneity is more of a possibility with ECAP and ECMAP with Route C processes. The deformation stress state is widely distributed in nature in modified ECAP processes than in conventional ECAP. In addition, the load requirements are also higher in modified ECAP processes with that of the... 

A general flow line model is developed to investigate the deformation behavior of Cu and Al through Bc route of Equal Channel Angular Pressing process at curved and sharp dies. Considering the Taylor theory, the obtained strain and strain rate from the flow line model and also using a modified version of ETMB model, the evolutions of nano-structure in the processed Cu and Al are predicted. Comparison between the modeling results and experimental data is carried out and a reasonable agreement is achieved. The results show that the deformation in the sharp die occurs in a narrow zone with higher strain rate than that in the curved die. Also, the cell size of the processed Cu is smaller than... 

Achieving high densification parameter is an essential factor for metal-based composites to represent excellent mechanical characteristics. Among various compaction methods, double-pressing double-sintering (DPDS) has gained the attraction of researchers to fabricate metal-matrix composites (MMCs) as an efficient technique over the last decade. In this process, the powder will be pre-pressed and then pre-sintered; it helps reduce work hardening and prepare the sample for better densification in the next pressing and sintering step. By employing the above-mentioned method, carbon nanotube (CNT) reinforced aluminum nanocomposites; ZrB2 reinforced copper nanocomposites; and CNT reinforced... 

A Monte Carlo model is modified by using Turnbull-Fisher nucleation rate model to simulate the ultra-fine microstructure evolution during annealing of pure copper processed by equal channel angular pressing (ECAP). The simulation is utilized to predict the grain size of pure copper samples at different annealing temperatures and pass numbers of ECAP. Also, in the simulation the constant nucleation rate model is assumed and a good agreement is achieved between the simulation results and experimental data. Thus, it can be concluded that the constant nucleation rate is prevailed during the microstructure evolution. © 2007 Elsevier B.V. All rights reserved  

By coupling a kinetic dislocation model and Monte Carlo algorithm, the recrystallized microstructure of severely deformed Oxygen Free High Conductivity Copper (OFHC) is predicted at different strains imposed by Equal-Channel- Angular-Pressing (ECAP) and annealing temperatures. From a flow field model, the strain rate distribution during the ECAP of the material in a curved die is calculated. Then using the kinetic dislocation model, the total dislocation density and correspondingly the stored energy after each ECAP pass is estimated. Utilizing the Monte Carlo algorithm and the stored energy, the recrystallized microstructure is predicted. The results show that the recrystallized grain size...