Showing 3 results for Hadavi
A. R. Kamali, S. M. M. Hadavi, H. Razavizadeh, J. Fahim,
Volume 5, Issue 2 (spring 2008 2008)
Abstract
Abstract: Production of titanium aluminides in TiO2-Al-Ca system has been investigated. For this
purpose, different compositions of raw materials were studied in a special reaction vessel. In a
special case, the non-completed reaction of TiO2 with Al and Ca resulted in the production of
granulates of titanium aluminides especially Ti3Al and other Ti – Al phases as the metallic product
and Ca12Al14O33 as the non-metallic product. Remelting of metallic granulates led to production of
TiAl ingot.
N Parvin, R Derakhshandeh Haghighi, M Naeimi, R Parastar Namin, M. M. Hadavi,
Volume 11, Issue 4 (December 2014)
Abstract
In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.
M. Ershadi Khameneh, H. Shahverdi, M. M. Hadavi,
Volume 12, Issue 4 (December 2015)
Abstract
Creep age forming (CAF) is one of the novel methods in aerospace industry that has been used to manufacture components of panels with improved mechanical properties and reduced fabrication cost. CAF is a combined age-hardening and stress-relaxation that are responsible for strengthening and forming, respectively. This paper deals with the experimental investigations of mechanical and springback properties of Al-Zn-Mg Al alloy in creep forming process. Creep forming experiments have been performed at temperatures of 120◦C and 180◦C for 6–72 h. Results indicated that yield stress and hardness of creep age formed specimens increased with increasing forming time and temperature, simultaneously induced deflection by stress-relaxation increased. Incorporating spring back and mechanical properties, it can be found that the appropriate forming cycle was 180 ◦C/24 h among all forming conditions. CAF Time increase to a certain extent increased mechanical properties. This can be attributed to presence of stress in CAF that causes the precipitates be finer because of creation more nucleation sites. Therefor the growth of precipitates, takes place at long time and postpones the decreasing of the yield stress
