The Influence of Bismuth, Antimony, and Strontium on Microstructure, Thermal, and Machinability of Aluminum-Silicon Alloy

Abstract

In this article, the influence of separate additions of bismuth, antimony, and strontium on microstructure, thermal, and machinability of Al-11%Si-2%Cu alloy (ADC12) has been reported. Additives depressed the aluminum-silicon eutectic growth temperature (T G ) and altered the silicon morphology. Different silicon morphologies, namely flake, lamellar, and fibrous influenced the main cutting force, feed force, and surface roughness during turning. Workpieces with fibrous silicon morphology produced the highest cutting force, feed force, and surface roughness while that of bismuth-containing workpieces produced the lowest cutting force, feed force, and the best surface roughness due to the formation of bismuth compound which acts as lubricant during turning. The results showed that the highest T G is related to the best surface roughness and as such the best machinable alloy investigated.

Neuro-fuzzy based predictive model for cutting force in CNC turning process of Al–Si–Cu cast alloy using modifier elements

“…An induction furnace was used to melt commercial Al-11.3Si-2Cu ingot and then pure Bi shots, pure Sb granules, and Al-10Sr master alloy were added in concentrations of 1wt.% Bismuth (Bi), 0.5 wt% Antimony (Sb), and 0.06 wt% strontium (Sr) respectively, according to the optimum concentration for each additive based on the author's previously published paper [7]. The molten metal was then poured at a temperature of 730 ± 5 °C into a permanent mould to fabricate the workpieces and the melted materials were stirred to achieve complete homogenization.…”

“…The reason could be related to the reduction of BUE during the machining of the alloy [2]. In addition, cutting force increased with increasing uncut chip thickness during the metal cutting process [7]. Figure 5 shows microstructure and image of the surface topography at highest cutting speed after machining the alloys.…”

“…The addition of modifier elements has been used to alter morphology of Silicon [7]. Farahany et al [8] investigated the role of Bismuth on solidification and microstructure of Al-Si alloys.…”

“…Furthermore, the addition of Bi changed growth of the eutectic Si phase. Another study has revealed that the addition of antimony (Sb) improved mechanical properties of the Al alloys with improving morphology of silicon shape [7].…”

Evaluation of cutting force and surface roughness in the dry turning of Al–Mg2Si in-situ metal matrix composite inoculated with bismuth using DOE approach

“…It has also been shown that the presence of Bi has a refinement effect on the morphology of eutectic silicon and Mg 2 Si reinforcement particles [24][25][26][27][28]. Additionally, Bi-containing work-piece showed the lowest cutting force and better surface roughness in Al-11Si-2Cu cast alloy in comparison to Sb and Sr containing work-pieces [29]. Moreover, it has been found that cutting force decreased and chip fragility increased by adding Bi to the 220 Al-2 %Cu-1.3%Si-0.4%Mg alloy [30].…”