Microstructure, Fracture and Mechanical Properties of ECAPed Aluminum P/M Alloy with Respect to the Porosity

Abstract

The main aim of this paper is to investigate the effects of different processing conditions on the behavior of a P/M (Powder Metallurgy) aluminum alloy with respect to the microstructure, fracture and mechanical properties. Moreover, the evolution of porosity as a consequence of pressing, sintering and ECAPing processes was investigated. A commercial Al-Mg-Si-Cu-Fe powder was used as material to be investigated. Different compacting pressures (400, 500, 600, 700 MPa) were applied. Specimens were dewaxed in a ventilated furnace at 400 °C for 60 min before sintering. Sintering was carried out in a vacuum furnace at 610 °C for 30 min. The specimens were ECAPed for 1 pass. The 2-dimensional quantitative image analysis was carried out by means of SEM and OM for the evaluation of the dimensional and morphological porosity characteristics. The detailed microstructure revealed the main features of sintering processes as well as secondary pores at the prior alloying particle sites. The tensile fracture surfaces in both studied processing condition (as-sintered and ECAP) show limited ductility, with fracture occurring on a plane normal to the tensile stress axis. Examination at higher magnifications revealed predominantly transparticle ductile features. In terms of mechanical properties, ECAP is almost doubling the tensile strength of the as-sintered materials

Determination of ductile fracture criteria for bulk and PM materials

“…Moreover, porosity has a significant influence on the stress distribution. As the stress is inhomogeneously distributed across the sample it can lead to reduction of the effective load bearing area [30][31][32][33]. The nCL critical value for HSLA was calculated 0.38-0.4, it was compared to that for AISI 1040 carbon steel with similar chemical composition.…”

Theoretical-Experimental Possibillities of Microstructure Quantification of Dispersion Strengthened Materials

“…The research proceeds in several directions the most important of which are new metallic alloys, ceramics, polymers, composites and amorphous materials. The composite materials with metallic, plastic and ceramic bases have already found their application in the machine industry, but their wider use is still limited by insufficient automation on their production resulting in their cost and by the need to elaborate new designs and techniques adapted for a better understanding and influencing of their properties, [1][2][3][4][5][6][7][8]. The mechanism of dispersion strengthening is based on the presence of a low volume fraction of fine secondary particles in the metal matrix, [9 -11].…”

Sliding Wear of TiCN PVD Coated Prealloyed Chromium Sintered Steel

“…The pores act as crack initiators, the distribution of stress is inhomogeneous across the cross section of the investigated material and reduces the effective load bearing area [2][3][4]. Besides porosity [5], the microstructure of the steel matrix has a significant effect on mechanical behaviour well as wear and fatigue characteristics [6][7][8][9]. Sliding wear is generally referred to as a type of wear generated by the sliding of one solid surface along another.…”