Influence of grain refiner addition and heat treatment on the mechanical properties of Al-Si alloy
In the present investigation, an attempt is made to study the effect of addition of grain refinement on Al-Si alloy, when it is subjected to the combined grain refiner addition (Al-5T-1B) and subjected to mechanical vibration and heat treatment. The material is tested for hardness property and dry sliding wear properties. The results of the present investigation indicate that there is a considerable improvement in the hardness valves, microstructure and resistance for wear.
Effects of T6 heat treatment on the microstructure, tensile properties, and fracture behavior of the modified A356 alloys
Abstract It is known that heat treatment causes the spheroidization of eutectic silicon. This paper presents the influence of T6 heat treatment on the microstructures, tensile properties, and fracture behavior of the A356 alloys modified by mischmetal containing La and Ce elements. Microstructural analysis showed that the size of eutectic silicon particles was greatly reduced and the extent of speroidisation of Si particles was remarkably improved for the modified A356 alloys. Comparison between the unmodified and modified alloys suggested that the values of mean diameter, roundness, and aspect ration of eutectic silicon particles were decreased by 48.10–56.85%, 49.55–54.52%, and 13.36–30.17%, respectively. The tensile properties of the modified A356 alloys can be enhanced, especially the ductility. These could be associated with the decrease of secondary dendrite arm spacing, spheroidization of fine eutectic silicon and precipitation hardening. Scanning electron microscopy (SEM) examination indicated that the ductile fracture mechanism was responsible for the modified alloys due to the existence of a couple of fine and uniformly distributed dimples. And the eutectic silicon particles and RE-containing intermetallic compounds provide the weak locations during the fracture process.
Tribological (wear) properties of aluminum–silicon eutectic base alloy under dry sliding condition
Low expansion, low density and high resistance to corrosion at ambient temperature make the aluminum–silicon alloys very suitable for wear resistance components in the automotive industry. In this study, wear behaviors of both the as-cast and heat-treated Al–Si alloy have been investigated. The cylindrical shaped wear testing specimens were prepared from cast ingot and some of the specimens were then heat-treated according to ASTM standard. Wear experiments on both samples were conducted with a pin-on-disk type wear testing apparatus. The test variables were the rotational speed, input weight, and time/sliding distance. The extent of wear damage was estimated by means of weight loss technique. The full heat-treatment has shown a great influence on the wear properties of the aluminum–silicon piston alloy. In general, the increase in wear with an increase in speed, input load and sliding distance was observed for both as-cast and heat-treated specimens.