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一、前言 美国宇航局(NASA)的新一代航天飞机(X-30)上,准备取消机身的防热瓦片来减轻自身重量,采用液态氢强制冷却机架和蒙皮,钛铝金属间化合物(α_2-Ti_3Al和γ-TiAl)是最有希望的候选材料。然而,许多学者研究指出,氢对Ti_3Al基金属间化合物的力学性能有较大的影响,且能形成氢化物。单相TiAl合金室温延性很差,通过添加合金元素(V、Cr、Mn)得到的双相(γ+α_2)TiAl合金,其延性有较好的改进,但是,新近研究表明,这种合金亦能形成氢化物,确实具有氢脆敏感性。尽管如此,人们依然努力寻找抗氢脆性能好的钛铝金属间化合物,最近K.S.Chan研究三种显微组织的Ti_3Al基合金后,认为精细网篮(fine basketweave)组织具有抗氢脆能力,且是很有发展的容忍氢材料。本文的目的是采用多种手段较深入研究网篮组织Ti_3Al基合金的氢脆敏感性及其氢致断裂行为。 二、材料和实验方法 本实验用料是真空非自耗电弧炉熔炼制成的铸锭,在β相区锻造加工至厚度16mm的板材,室温冷却。合金成分为Ti-24Al-11Nb(at％)。将锻造合金板材经线切割
I. Introduction NASA’s new generation of spacecraft (X-30), ready to cancel the body’s heat-resistant tiles to reduce their own weight, the use of liquid hydrogen to force cooling rack and skin, titanium aluminum metal Compounds (α_2-Ti_3Al and γ-TiAl) are the most promising candidate materials. However, many scholars have pointed out that hydrogen has a greater impact on the mechanical properties of Ti_3Al-based intermetallic compounds, and can form hydride. Single phase TiAl alloys have poor ductility at room temperature. Ductility (γ + α_2) TiAl alloys obtained by adding alloying elements (V, Cr and Mn) have good ductility. However, recent studies have shown that this alloy Can form hydride, does have hydrogen embrittlement sensitivity. In spite of this, people are still struggling to find titanium-aluminum intermetallic compounds with good resistance to hydrogen embrittlement. Recently, KSChan considered three kinds of microstructured Ti_3Al-based alloys and considered that the fine basketweave tissue possesses resistance to hydrogen embrittlement and It is a great development tolerance hydrogen material. The purpose of this paper is to study the hydrogen embrittlement susceptibility and hydrogen induced fracture behavior of Ti_3Al-based alloy by a variety of methods. Second, the material and experimental methods The experimental material is vacuum non-consumable arc furnace ingot ingot, in the β-phase forging to a thickness of 16mm plate, cooled at room temperature. The alloy composition is Ti-24Al-11Nb (at%). Forged alloy sheet by wire cutting