Alloy development and reheating process exploration of Al–Si casting alloys with globular grains for thixoforming

Abstract

A novel two-stage reheating process with new alloy design has been developed to improve the microstructure morphology of semi-solid Al-Si casting aluminum alloy for thixoforming. The process consists of first reheating the material to the liquidus temperature, holding for 5 minutes, and then lowering to the predetermined two-stage reheating temperature between 843 -863 K and holding for 10 minutes. The experimentally-obtained grain diameter, roundness, and the amount of liquid trapped within the solid phase were characterized, along with the microstructure obtained using the traditional feedstock reheating process. The Wilcox test (with α=0.05) was then applied to statistically analyze the measured differences in the microstructures obtained using the two different processing routes. It was found that a refined near-spherical structure with uniform globule size, higher sphericity, lower coarsening rate constant, and less entrapped liquid was obtained via the new two-stage reheating process in comparison with the microstructure obtained using the traditional feedstock reheating process.

Evaluation of microstructure and mechanical properties of M-SIMA processed Al–7Si alloy

“…Among the semisolid processes, the SIMA process is more popular to develop Al–Si alloys with the spherical primary α-Al grain and divorced eutectic Si which significantly improves the strength and ductility as compared to as-cast alloy [19]. The production of Al–Si alloys by the SIMA process is selected due to its wide solidus and liquidus temperature range and high fluidity [20]. These characteristics play a vital role in the processing of Al–Si alloys to achieve the desired quality of the products [21].…”

Contact around a Sharp Corner with Small Scale Plasticity

“…The stress field around a contact interface with a sharp corner is closely related to various failures such as wear, fatigue and plastic yielding, which significantly limit the life of various engineering components [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The analysis of contact stress around these area is important in understanding the onset and propagation of those failures: it will provide guidelines for the design of contact components so that the damage can be limited [11,12,[15][16][17][18][19][20][21].…”

Analysis on micro-structure and mechanical properties of Mg-Gd-Y-Nd-Zr alloy and its reinforcement mechanism

“…The micro-structure performance and mechanical properties of melt alloy can be improved by adding certain amount of rare earth elements in it, especially in the area of oxidation resistance and creep. So the application researches on rare earth elements in Mg-RE alloy attract scholars' attention [1][2][3][4][5]. The rare earth element Gd in M-RE liquid alloy has a high solid solubility and can rapidly be weakened with the decreasing of temperature, which can realize a time limitation of melt Mg alloy, so Gd is considered to a typical rare earth element to improve the performance of Mg alloy [6][7].…”