The development of effective grain refiner for the production of high performance light metal castings

铝硅（Al-Si）合金是重要的合金，因为它们重量轻（2.7 g/cc），易于回收，耐腐蚀，耐用和环保。与钢（7.8 g/cc）相比，它们具有更高的强度重量比。90%的铝型材铸件是基于这些铝硅合金，目前，每年约有500万吨铝硅合金用于汽车工业。2006年生产的汽车平均含110-145公斤铝，而钢约为1000公斤。生命周期分析表明，用铝代替钢每减轻100公斤的重量，在汽车的使用寿命（20万公里）内可节省900升汽油，减少2000公斤二氧化碳（10克/公里）。对于轻金属工业来说，进一步增加这些轻质铝硅合金的使用，以取代运输部门的钢，最大的问题是缺乏延展性和屈服强度，这与大晶粒结构、缺陷和大金属间颗粒有关。由于Al-Si合金难以细化晶粒，目前由于铸造缺陷过多和机械性能不足，限制了其广泛采用。这些合金中较高的Si含量导致晶粒较大，这使得铸造困难，从而导致非常高的废品率，对于高价值的关键部件高达60%。由于Si和Ti之间的反应，用于非铸造（锻造）铝合金的Ti基晶粒细化剂在铸造Al-Si合金中效果较差。Brunel发明了一种有效的晶粒细化剂，可以彻底改变这些Al-Si铸造合金的铸造工艺，显著减少铸造缺陷，并产生卓越的机械性能，尽管（故意）限制宣传，但已经在材料供应链中产生了显著的市场兴趣。布鲁内尔晶粒细化剂（BGR）改善了多种铝合金的浇注性能；消除铸件常见的热撕裂问题；它提高了急需的抗拉强度和延展性；提高整个部件机械性能的均匀性；它使薄壁铸造结构；而且它可以容忍高杂质水平（铝废料现在可以制造出更高的性能）。此外，它有望使用砂型铸造大型和复杂形状的结构，并降低高价值部件制造过程中的高废品率（高达60%）。布鲁内尔谷物精炼厂的独特卖点是，它是非常有效的散装铸件和容易雇用的行业。目前还没有有效的Al-Si铸件晶粒细化剂，以前难以生产高性能无缺陷的大块铸件现在可以很容易地加工。它为广泛的铸造技术带来好处，应该能够生产具有卓越性能的铸件，使铝取代汽车行业中越来越多的钢零件。这将使英国走在冶金技术发展的前沿。由于重量轻，能源消耗和二氧化碳排放的减少，预计将带来非常可观的环境效益。

Aluminium-Silicon (Al-Si) alloys are important alloys as they are lightweight (2.7 g/cc), easily recycled, corrosion resistant, durable and environmentally friendly. In comparison with steel (7.8 g/cc), they have higher strength to weight ratio. 90% of aluminium shape castings are based on these Al-Si alloys and currently, ~ 5 million tonnes per annum are being used in automotive industry. The average car manufactured in 2006 contained between 110-145 kg of Aluminium, compared to ~1000 Kg of Steel. Life cycle analysis suggest that, a 100 kg weight reduction through substituting Steel with Aluminium parts would result in a saving of 900 litres of petrol during the car's life span (200,000 km) and 2,000Kg of CO2 savings (10 g/km). The big problem for the light metal industry in increasing the further use of these lightweight Al-Si alloys with respect to replacing steel in the transport sector is the lack of ductility and yield strength associated with the large grain structure, defects and large intermetallic particles. Since Al-Si alloys are difficult to grain refine, widespread adoption is currently constrained due to excessive casting defects and inadequate mechanical properties. Higher Si levels in these alloys results in large grains, which make casting difficult, thus resulting in very high rejection rates, up to 60% for high value critical components. Ti based grain refiners used for non-cast (wrought) Al alloys are less effective in cast Al-Si alloys due to reaction between Si and Ti. Brunel has invented an effective grain refiner that can revolutionize the foundry casting process for these Al-Si casting alloys, significantly reducing the casting defects and producing superior mechanical properties that, despite (deliberately) limited publicity, is already generating significant market interest within the materials supply chain. The Brunel grain refiner (BGR) improves castability of a wide range of aluminium alloys; eliminates hot-tearing, a common problem in castings; it improves much needed tensile strength and ductility; improves homogeneity in mechanical properties across the component; it enables thin-wall cast structures; and it tolerates high impurity levels (aluminium scrap can now be manufactured with superior properties). Additionally, it is expected to enable the casting of large and complex shaped structures using sand moulds and reduce the high (up to 60%) rejection rate during manufacture of high value components.The unique selling points of the Brunel Grain refiner are that it is highly effective for bulk castings and easily employable by the industry. Currently there exists no effective grain refiner for Al-Si castings and previously difficult to produce high performance bulk castings without defects can now be easily processed.Delivering benefits to a wide range of casting techniques, it should enable the production of castings with superior properties, allowing aluminium to replace a growing proportion of steel parts in the automotive sector. This will put the UK in the forefront of metallurgical technological developments. Very substantial environmental benefits are foreseen due to light-weighting and concomitant reductions in energy consumed and CO2 emitted.