Mechanical properties of Al-60 Pct SiCp composites alloyed with Mg

Abstract

In the present work, the effect of an Mg addition on the mechanical properties of the Al-60 vol pct SiCp composites were investigated by uniaxial compression, three-point bending, impact and wear tests (composite-metal and composite-abrasive types). The composites were produced by the pressure-infiltration technique. The composition of the Al matrix was varied between 0 and 8 pct Mg. The mean diameter of the SiC particles was 23 m. Upon addition of Mg, Mg 2 Si precipitated in the matrix and the amount of the porosity dramatically decreased. Mg-alloyed-matrix composites exhibited higher strength, lower toughness, and higher wear resistance than pure-Al-matrix composites. During composite-metal wear testing, wear progressed in two sequential periods (running-in and steady state). Weight loss during wear testing decreased with increasing Mg content of the matrix. The degree of improvement of abrasive resistance depended on the abrasive-grain size. Above 200°C, the composite-abrasive wear resistance decreased with increasing test temperature for all materials.

Production and corrosion behaviours of the Al–12Si–XMg alloys containing in situ Mg2Si particles

“…The increase in compression strength is continual with increasing the Mg content. The mechanism of hardening was believed to be due to the combination of solid solution and formation of the in situ particles being obstacles to the movement of dislocations [5,29].…”

“…An alternative approach to the production of Al-Si alloys with improved mechanical properties is to reinforce the matrix with hard ceramic particles, such as SiC and Al 2 O 3 [4,5]. It should be mentioned that most of the metal matrix composites suffer from thermodynamic instability of interfaces among the ceramic reinforcement/matrix and poor wettability of the reinforcement [6].…”

Effect of extrusion ratio on the wear behaviour of Al–Si and Al–Mg alloys

“…Previous studies state that the formation of iron oxide on the surface decreases the amount of wear [21,39,[43][44][45]. EDS analyses illustrate that oxygen and iron peaks increase together with the increase in the ratio of extrusion, ultimately forming a thicker iron oxide layer on the worn surface [3,40]. It proves that an alloy extruded at a high ratio will have a higher level of wear resistance.…”

“…4A and C that the grains of the Al-Si alloy extruded at the ratio of 2 are elongated more than the ones in the Al-Mg alloy. It proves that Si, as the alloying element, increases its ductility in the aluminium alloy and grains elongate more; additionally, it is proved that the formability of the Al-Si alloy is better than the Al-Mg alloy [39,8,40]. Table 2 illustrates the results of the microhardness test (HMV) conducted using a 50 g load for as-cast and extruded Al-Si and Al-Mg alloys.…”

“…EDS analyses show the traces of Al, Si, Fe, Cr and O peaks on the worn surface. While Al, Si and Mg elements were already present in the worn material, Fe and Cr were transferred over from the counter material [8,40]. EDS analyses show an oxygen peak caused by the iron oxide formed as a result of the Fe reacting with the oxygen in the atmosphere [6].…”