高温金属结构材料单晶制备及其研究进展

Preparation and Development of Single Crystals of High Temperature Structural Metal Materials

高温金属结构材料具有极其突出的高温力学性能、抗氧化能力等,被广泛用于航空航天、武器装备、核电装备等重要领域。其单晶不存在晶界破坏,具有韧-脆转变温度低、高温结构性能稳定等优点,使用温度比相同成分的传统柱状晶提高50~100℃,安全服役寿命得以显著提高,因而高温金属结构材料单晶的制备、取向及其性能已经成为当前高温结构材料领域研究的热点。该综述简要回顾了高温金属结构材料单晶发展历程,重点且系统论述了近年来国内外最新研究进展,分别介绍了气相沉积法、电子束悬浮区域熔炼法、光束悬浮区域熔炼法、等离子弧熔炼法、增材制造技术等制备工艺、原理、优缺点及最新研究现状,总结了不同制备工艺对高温金属结构材料单晶组织、性能的影响及其作用规律,并展望了未来的研究趋势以及应用前景,以期对高温金属结构材料的优化和发展提供借鉴意义。

The high-temperature structural metal materials had been widely used in the fields of aerospace,weapons and nuclear systems due to their extremely outstanding high-temperature mechanical properties and oxidation resistance.Since the single crystals displayed the advantages of no grain boundary damage,low ductile-brittle transition temperature and high-temperature structural stability,their service temperature could be improved by 50~100℃compared to the polycrystal alloys under the same compositions,obtaining an enhanced service life.The development of single crystals of high-temperature metal structural material was helpful to explore their basic physical and chemical properties,and various crystallographic properties.At the same time,it also provided reliable data support for the development and application of new materials,and accelerated the development of new materials.At present,many methods had been developed to prepare single crystals.However,due to the strict requirements of high-temperature structural materials for the service temperature and the service life,it was necessary to strictly control the solidification process and reduce the internal microstructure defects.Via the traditional preparation methods,such as the Czochralski method,a large number of inclusions in ceramic crucibles were difficult to avoid,reducing production efficiency.There was still a gap between the current material production methods and the idea of pursuing high efficiency,short time and low consumables.In this paper,several promising methods of preparing high-temperature metal single crystals were introduced.Chemical vapor deposition(CVD)produced the solid materials by reactive deposition on the substrate surface,which could significantly reduce the preparation temperature,making the process easy to operate and low in cost,and was usually used to prepare metal single-crystal films.In the zone melting technique process,the material was locally heated and melted to achieve directional solidification,and the grains in the melting zone were rearranged,and thus the metal single crystals with preferred orientations can be prepared.The plasma arc method could produce the high-energy plasma arc with low voltage and high current,realizing the preparation of the large-size metal single wafer,rod and tube.Additive manufacturing technology had developed rapidly to prepare and repair engine single-crystal turbine blades,because it could realize rapid prototype manufacturing and customized production of single small batch parts.This paper systematically introduced these methods of preparation technologies,principles,advantages,disadvantages and the latest research advances,and summarized the different preparation processes of single crystals of high-temperature metal structure materials.Moreover,we analyzed the influences of different preparation methods on the the microstructures,properties of single crystals,and investigated influence laws,and gave the future research trends and the application prospects,providing a reference or guidance to the optimization of high-temperature structure metal materials.