Growth of Nickel-Base Superalloy Single Crystals

[9322353]镍基高温合金是我国航空航天工业和能源工业某些领域的关键材料。镍基高温合金单晶在高温燃气轮机中表现出优异的性能。这项资助支持了一项大学-工业合作，通过从液体熔体中提取镍基高温合金的形状单晶。单晶在威斯康辛大学生长，并在Howmet公司进行测试，Howmet公司是美国高温燃气轮机用镍基高温合金单晶的主要生产商，目的是证明生长低成本、高质量的恒定截面单晶（棒、棒、板和管）的可行性。这些晶体在不需要复杂形状的应用中很有用，例如涡轮发动机燃烧室内衬的单晶片（气体混合物点燃的地方）。其优点是不需要制备和去除陶瓷外壳模具的许多步骤，并且晶体不限于相对较短的长度，这与传统的镍基高温合金通过熔模铸造的晶体生长不同。人们的注意力集中在长达2英尺的单晶片的生长上。使用了威斯康星大学晶体生长实验室最近开发的一种改进的拉形晶体技术，并由Howmet进行了单晶的热处理和初步筛选测试。将制作一盘录像带，显示所建议的工作的结果，并向高温合金工业分发副本。它还将用于威斯康星大学的两门本科材料加工课程。＊＊＊

9322353 Kuo Nickel-base superalloys are critical materials to our aerospace industry and to some areas of our energy industry. Single crystals of nickel-base superalloys have demonstrated excellent performance in high-temperature gas turbines. This grant supports a university-industry collaboration on the growth of shaped single crystals of nickel-base superalloys by pulling from liquid melts. Single crystals are grown at the University of Wisconsin and tested at Howmet Corporation, a major producer of single crystals of nickel-base superalloys for high-temperature gas turbines in the U.S. The objective is to demonstrate the feasibility of growing low-cost, high-quality single crystals of constant cross-sections (rods, bars, sheets and tubes). These crystals are useful for applications where complicated shapes are not required, e.g., single crystal sheets for turbine engine combustor liners (where gas mixtures ignite). An advantage is that numerous steps involved in the preparation and removal of ceramic shell molds are not required and the crystals are not limited to relatively short lengths, unlike conventional crystal growth of nickel-base superalloys by investment casting. Attention is focused on growth of single crystal sheets up to 2 feet long. An improved technique for pulling shaped crystals, recently developed at the University of Wisconsin's crystal growth laboratory, is used and heat treating and preliminary screening tests of the single crystals are conducted by Howmet. %%% A videotape movie showing the results of the proposed work will be made and copies distributed to the superalloy industry. It will also be used in two undergraduate materials processing courses at the University of Wisconsin. ***