We recently 3D printed (SLM) hypereutectic (high Si)% Al-Si-alloys and chemically removed the Al afterwards (via HCl (aq)) in order do get a porous structure, which worked quite well.
1.) I was wondering about the maximum Si content with which one could work/print. From the phase diagram I only see the issue, that the freezing ranges increases with higher Si content, which could lead to more cracking. But in a book it was mentioned, that alloys "made by powder metallurgy may go as high as 40-50% Si" - is this just regarding the practical usage or is there some kind of limit I am not seeing?
2.) Does anyone have an educated guess about the parting limit during dealloying for such a hypereutectic alloy? I only found some limit for systems like AuAg, which show perfect solubility. Would the parting limit be higher or lower in a hypereutectic alloy - any ideas?
The maximum silicon (Si) content in aluminum-silicon (Al-Si) alloys can vary depending on the specific alloy composition and application. However, one of the commonly used Al-Si alloy series is the 3xx.x series, which typically contains silicon in the range of 1-20%. For example:
- 3003 alloy: Contains about 1% silicon.
- 6061 alloy: Contains about 1-1.8% silicon.
Higher silicon content can be found in specialized alloys, such as some of the 4xx.x series and 6xx.x series, which may contain silicon ranging from 4-20% or more.
Regarding the parting limit during dealloying or chemical leaching of Al-Si alloys, the extent of dealloying is influenced by various factors including the alloy composition, microstructure, processing conditions, and the specific dealloying method employed. There is no universally fixed "parting limit" as it depends on these aforementioned factors.
Dealloying involves selectively dissolving one component (often less noble) from an alloy leaving behind a porous structure enriched in the more noble component. During dealloying of Al-Si alloys, silicon is typically less noble than aluminum, so the silicon tends to dissolve more readily.
The extent of dealloying or the parting limit can vary based on the conditions of the dealloying process, the specific alloy composition, and the desired final structure. Detailed studies and experiments would be needed to determine the precise parting limit for a particular Al-Si alloy under specific dealloying conditions. It's important to consider the purpose of the dealloying and tailor the process to achieve the desired properties and structure in the remaining material after dealloying.
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