HIGH TEMPERATURE MECHANICAL PROPERTIES OF Al-Al4C3 COMPOSITE PRODUCED BY MECHANICAL ALLOYING

Abstract

A method of mechanical alloying process is described. It was proved that the transformation efficiency of carbon to Al 4 C 3 by heat treatment of aluminium with the porous furnace black and electrographite at temperatures 723-873 K and time periods 1-10 hours is higher than that of the hard cracked graphite. The size of Al 4 C 3 dispersed phase was measured on thin foil and it was constant and as small as 30 nm. Subgrain size measured in the range of 100 grains in thin foils depended on the carbon type.. It ranged from 0.3 to 0.7 μm. Mechanical properties were analyzed in a microstructural matrix (after extrusion) as well as in nano-matrix The temperature dependence of ductility, and reduction of area in the temperature range of 623-723 K and strain rate of 10-1 s-1 , indicated a considerable increase of properties. In a case when the volume fraction of Al 4 C 3 changes from lower to higher, the grain rotation mechanism dominates instead of the grain boundary sliding. Creep parameters for Al-Al 4 C 3 systems and commercial IN9021 and IN9052 systems were compared. The dependence of the minimum deflection rate on the applied force as well as the dependence of the time to fracture on the applied force for two temperature levels (623 and 723 K) by small punch testing is depicted. The anisotropy of the creep properties and fracture using small punch tests for the Al-Al 4 C 3 system produced by ECAP were analyzed.

Evaluation of Hight Purity Aluminium After Asymmetric Rolling at Ambient and Cryogenic Temperatures

“…Deformation at cryogenic temperature has emerged as a potential route to develop ultrafine grained (UFG) material with improved mechanical properties. The formation of UFG microstructures in various Al alloys has been investigated by many researchers [16][17][18] through various techniques such as asymmetric cryorolling, symmetric cryorolling, cryo-ECAP, etc. Yu et.…”

SYNTHESIS OF Cu2ZnSnS4 BY MECHANICAL ALLOYING METHOD FOR THERMOELECTRIC APPLICATION

“…The formation mechanism of CZTS during high-energy ball mill is attributed tothe diffusion process, which takes place when particles are cold-welded together. Heavy plastic deformations during milling createa variety of crystal defects such asdislocations, vacancies, stacking faults, and increasethe grain boundaries, and so, enhances the diffusion process.In addition, slightly temperature raise during milling further aids the diffusion process; consequently, true compound is formed.The specific times required to develop a given structure in any system depends on the initial particle size, characteristics of the ingredients,and the operating parameters of the equipment [21][22][23].…”

Fracture Analysis and Local Mechanical Properties of Copper Processed by Ecar

“…4 shows a crack which was formed most probably at a boundary of original grains. Microcracks started to appear at sites of microvoids and in triple grain junctions [14][15][16][17][18]. It was most probably initiated by dislocation mechanism [10].…”