文章信息/Info

Title:

Growth of Single Crystal Alloy under Microgravity Condition

作者:

羅興宏; 晉冬艷; 任玉虎

中國科學(xué)院金屬研究所，中國科學(xué)院核用材料與安全評價(jià)重點(diǎn)實(shí)驗(yàn)室

Author(s):

LUO Xinghong;  JIN Dongyan;  REN Yuhu

CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences,

關(guān)鍵詞:

空間; 微重力; 單晶合金; 晶體生長; 凝固; 缺陷

Keywords:

Space;  Microgravity;  Single Crystal Alloy;  Crystal Growth;  Solidification;  Defects

DOI:

10.7502/j.issn.1674-3962.2017.04.03

文獻(xiàn)標(biāo)志碼:

A

摘要:

單晶合金由于沒有晶界缺陷而具有特殊的理化性能，如鎳基單晶高溫合金是先進(jìn)航空航天發(fā)動(dòng)機(jī)和燃?xì)鉁u輪發(fā)動(dòng)機(jī)關(guān)鍵材料，具有優(yōu)異的高溫使役性能。單晶合金的特色結(jié)構(gòu)決定了它只能通過凝固的方式獲得，因而凝固過程對單晶合金的組織結(jié)構(gòu)、成分分布乃至理化性能具有難以磨滅的影響。如以枝晶結(jié)構(gòu)為主要特征的單晶合金中的枝晶結(jié)構(gòu)參數(shù)、合金元素的宏觀與微觀偏析都與凝固過程參數(shù)，如凝固速度、溫度梯度等，密切相關(guān)。研究表明，重力導(dǎo)致的各項(xiàng)效應(yīng)，如浮力對流、沉降和流體靜壓等，直接或間接地影響凝固過程參數(shù)，并且是導(dǎo)致成分偏析和凝固缺陷的重要原因。但在常規(guī)地面條件下由于無法有效去除重力影響，因而難以清晰揭示凝固過程中的重力效應(yīng)及其作用規(guī)律。而在微重力環(huán)境中，這一難題將迎刃而解。因此，近些年來國內(nèi)外一些學(xué)者利用空間或模擬微重力環(huán)境，對重力對單晶凝固行為的影響及其在缺陷形成中的作用進(jìn)行了研究。這些研究對于獲得良好的單晶凝固組織、避免凝固缺陷的形成，以及提高單晶合金的質(zhì)量和性能都有著重要的意義。本文對目前國內(nèi)外微重力下單晶生長研究的相關(guān)進(jìn)展進(jìn)行綜述并對未來研究進(jìn)行展望。

Abstract:

Without grain boundary defects, single crystal alloys possess special physical and chemical properties, e.g., as key materials for advanced aerospace engines and gas turbine engines, Ni-based single crystal superalloys have excellent high temperature performance. The characteristics of single crystal alloys determines they can only be obtained by means of solidification and therefore, the solidification process has enduring influence on microstructure, composition distribution and physical and chemical properties of single crystal alloys. For instance, as dendritic structure being the main characteristics, dendritic parameters and macro and micro element segregation of single crystal alloy are closely related with the solidification process parameters, such as solidification speed, temperature gradient and so on. Researches show that, the effects caused by gravity, such as buoyancy convection, sedimentation and hydrostatic pressure, etc., directly or indirectly affect the solidification process parameters, and become the important causes leading to the composition segregation and solidification defects. However, the effect of gravity cannot be effectively removed under conventional terrestrial condition, and it is difficult to clearly reveal the gravity effects in the process of solidification and their mechanisms. Hopefully, this problem will be solved under microgravity environments. Therefore, in recent years, taking advantage of space or simulated microgravity environments, the gravity effects on single crystal solidification behavior and their roles in the course of defects forming were studied by domestic and international scholars. These researches are of great significance for obtaining better single crystal solidification microstructure, avoiding the formation of solidification defects and improving the quality and performance of single crystal alloys. This paper reviews the recent domestic and international research progress on single crystal growth under microgravity and prospects for future researches.