SBIR Phase I: Novel Casting Process for Developing a Carbon Modified Hyper-Eutectic Aluminum-Silicon Alloy for Forging Wear Resistant Parts

这个小企业创新研究第一阶段项目提出开发一种基于4032铝锻造合金成分的20-25% Si合金，具有低密度和高耐磨性。拟议的第一阶段研究建立在熔体中的碳分散，可以增加铸造铝合金的可加工性和流动性。为了在过共晶合金中实现这些优势，建议在熔体加工过程中调整铝合金中的碳和铜含量，并在凝固过程中在Al-Si共晶中析出初生硅、碳化物和石墨薄片等轴颗粒。这些微粒子和纳米粒子将提供更高的耐磨性、模量和韧性。在本研究中存在着重大的挑战，包括在铸锭凝固过程中可能析出不需要的针状硅、不可接受的收缩率、氢脆、偏析等。高硅含量会显著降低合金在加工过程中的凝固和均质化动力学，使合金难以获得均匀的性能和微观组织。由于这项研究的目的是利用一种新的铸造工艺创造一种新的合金成分，它将在凝固和变形加工方面产生相当多的新的基础知识。该项目的更广泛的影响/商业潜力是，一个新的市场将为可热处理的高完整性可加工锻造过共晶零件打开大门。目前，大多数铝硅合金部件仅限于铸造结构，其强度和耐磨性超过了物理缺陷、废品率和高加工成本的额外测试成本。汽车发动机的应用包括活塞、气缸盖和连杆，其中耐磨性和轻量化很重要，以及计算机设备制造，其中热性能、重量和刚性至关重要。

This Small Business Innovation Research Phase I project proposes to develop a 20-25% Si alloy based on the 4032 aluminum forging alloy composition that has low density and high wear resistance. The proposed Phase I research builds upon carbon dispersion in the melt that can increase machinability and fluidity of cast aluminum alloys. To achieve these advantages in hyper-eutectic alloys, it is proposed to adjust the carbon and copper contents in the aluminum alloy during melt processing, and to precipitate during solidification equiaxed particles of primary silicon, carbides and graphite flakes in the Al-Si eutectic. These micro- and nano-particles will provide for higher wear resistance, modulus and toughness. There are significant challenges in this research including the possibility of precipitation of undesired acicular silicon, unacceptable shrinkage, hydrogen embrittlement, segregation etc. during ingot solidification. The high silicon content can significantly reduce solidification and homogeniezation kinetics during processing making it hard to achieve uniform properties and microstructure. Since this research aims to create a new alloy composition using a novel casting process, it will generate considerable new fundamental knowledge in solidification and deformation processing. The broader impact/commercial potential of this project is that a new market will open up to higher-integrity machinable forged hyper-eutectic parts that are heat treatable. Currently, most aluminum-silicon alloy components are limited to cast structures where their strength and wear capabilities override the additional costs of testing for physical defects, rejections, and high costs of machining. Applications in automotive engines include pistons, cylinder heads and connecting rods where wear resistance and light weight is important, and computer equipment manufacturing where thermal properties, weight and rigidity are critical.