There are several facets of aluminum when it comes to sustainability. While it helps to save fuel due to its low density, producing it from ores is very energy-intensive. Recycling it shifts the balance towards higher sustainability, because the energy needed to melt aluminum from scrap is only about 5% of that consumed in ore reduction. The amount of aluminum available for recycling is estimated to double by 2050. This offers an opportunity to bring the metallurgical sector closer to a circular economy. A challenge is that large amounts of scrap are post-consumer scrap, containing high levels of elemental contamination. This has to be taken into account in more sustainable alloy design strategies. A “green aluminum” trend has already triggered a new trading platform for low-carbon aluminum at the London Metal Exchange (2020). The trend may lead to limits on the use of less-sustainable materials in future products. The shift from primary synthesis (ore reduction) to secondary synthesis (scrap melting) requires to gain better understanding of how multiple scrap-related contaminant elements act on aluminum alloys and how future alloys can be designed upfront to become scrap-compatible and composition-tolerant. The paper therefore discusses the influence of scrap-related impurities on the thermodynamics and kinetics of precipitation reactions and their mechanical and electrochemical effects; impurity effects on precipitation-free zones around grain boundaries; their effects on casting microstructures; and the possibilities presented by adjusting processing parameters and the associated mechanical, functional and chemical properties. The objective is to foster the design and production of aluminum alloys with the highest possible scrap fractions, using even low-quality scrap and scrap types which match only a few target alloys when recycled.

在可持续性方面，铝有几个方面。虽然由于其低密度有助于节省燃料，但从矿石中生产它是非常耗能的。回收它使平衡转向更高的可持续性，因为从废料中熔化铝所需的能量仅为矿石还原消耗的能量的 5% 左右。预计到 2050 年，可供回收利用的铝量将翻一番。这为使冶金行业更接近循环经济提供了机会。一个挑战是大量废料是消费后废料，含有高水平的元素污染。在更可持续的合金设计策略中必须考虑到这一点。“绿色铝”趋势已经在伦敦金属交易所（2020）引发了新的低碳铝交易平台。这一趋势可能会限制在未来产品中使用不太可持续的材料。从初级合成（矿石还原）到次级合成（废料熔化）的转变需要更好地了解多种与废料相关的污染物元素如何作用于铝合金，以及如何预先设计未来的合金以使其与废料兼容和成分耐受. 因此，本文讨论了与废料相关的杂质对沉淀反应的热力学和动力学及其机械和电化学效应的影响；杂质对晶界周围无沉淀区的影响；它们对铸件微观结构的影响；以及通过调整工艺参数和相关的机械、功能和化学特性所呈现的可能性。