Al-Si alloy for thermal storage applications-a review

Abstract

In regions that experience abundant sunshine, solar radiation emanating from the sun constantly generates significant thermal energy which has been an established potential source of harvestable clean energy. But an enormous amount of this form of renewable energy reaching the earth’s crust gets re-emitted back into the space at sunset period without being harnessed. There is a special need for researches to further develop thermal storage alternatives with high thermal capacity, good thermal transfer rate, portable, cost effective and durable. From literature, aluminum and silicon alloys have proved to be one of the most efficient thermal storage materials for medium to high temperature storage applications. It has been shown that different combinations of these gives different results depending on the application the alloy is to be used for. This paper reviews the application of Al-Si alloys for thermal storage with superior properties to Al-Cu, Al-Mg, Al-Cu-Zn, Al-Si-Mg and Al-Si-Cu alloys. The making of Al-Si for thermal storage through liquid and solid metallurgical processes were also highlighted.

Scalable Synthesis of Porous Silicon by Acid Etching of Atomized Al–Si Alloy Powder for Lithium-Ion Batteries

“…For a hypereutectic Al−Si composition, the primary Si, eutectic Al, and eutectic Si all decrease in grain size with an increased cooling rate. 56,59 In other words, as shown in Figure S5, the grain sizes of primary Al, eutectic Al, eutectic Si, and eutectic Si of all atomized Al−Si alloys decreased to the nanoscale.…”

“…In addition, increasing the cooling rate causes the eutectic Si crystallized in the resinous form to change from a coarse lamellar structure to fine particles. For a hypereutectic Al–Si composition, the primary Si, eutectic Al, and eutectic Si all decrease in grain size with an increased cooling rate. , In other words, as shown in Figure S5, the grain sizes of primary Al, eutectic Al, eutectic Si, and eutectic Si of all atomized Al–Si alloys decreased to the nanoscale.…”

“…The microstructure of Al–Si alloys solidifying from the Al–Si liquid phase has been discussed in the literature, and the morphologies of primary Al, eutectic Al, eutectic Si, and primary Si are known to vary greatly depending on the solidification conditions (i.e., cooling and growth rates) and trace additions. ,,− The eutectic point of Al–Si alloys has been reported to shift to the high-Si side upon rapid cooling and solidification from solution Figure S5 shows cross-sectional SEM or backscattered electron (BSE) images and EDS results for the atomized Al 88 Si 12 , Al 81 Si 19 , and Al 75 Si 25 particles.…”

“…In a hypoeutectic Al–Si alloy (<12.6 wt % Si), primary Al crystallizes from the melt, resinous eutectic Si crystallizes at the eutectic point, and eutectic Al crystallizes around the eutectic Si. In hypereutectic Al–Si alloys (>12.6 wt % Si), lumpy primary Si crystallizes from the melt as it solidifies, and resinous eutectic Si crystallizes as well as eutectic Al. , Many studies have reported on the solidification microstructures of hypoeutectic, eutectic, and hypereutectic Al–Si alloys, − and the morphologies of primary Al, eutectic Si, and primary Si are known to vary significantly depending on the solidification conditions (i.e., cooling and growth rates) and Si composition. − When Al–Si alloys are rapidly solidified from solution as in gas atomization, the eutectic point shifts to the high-Si side . In other words, Al–Si alloy powders prepared by gas atomization have a microstructure consisting of primary Al, eutectic Si, and eutectic Al without crystallization of primary Si at hypereutectic Al–Si compositions. , Because of the rapid solidification, the grain size of primary Al decreases with increasing cooling rate at hypoeutectic and eutectic Al–Si compositions.…”

“…In hypereutectic Al−Si alloys (>12.6 wt % Si), lumpy primary Si crystallizes from the melt as it solidifies, and resinous eutectic Si crystallizes as well as eutectic Al. 55,56 Many studies have reported on the solidification microstructures of hypoeutectic, eutectic, and hypereutectic Al−Si alloys, 55−61 and the morphologies of primary Al, eutectic Si, and primary Si are known to vary significantly depending on the solidification conditions (i.e., cooling and growth rates) and Si composition. 56−59 When Al−Si alloys are rapidly solidified from solution as in gas atomization, the eutectic point shifts to the high-Si side.…”