Inconel 718合金中间相转变机制及其组织控制

With the development of engine, rocket and so on, the high-temperature alloy, especially the most widely used Inconel 718 alloy is expected to exhibit excellent high-temperature strength. The γ″→δ transformation mechanism is essential for understanding the microstructural stability and improving the mechanical properties of Inconel 718 alloy. In this regard, the storage energy during processing or the composition variation will affect the γ″ and δ precipitation kinetics, and thereby the γ″→δ transformation. Meanwhile, the effective modulation on the processing craft and the alloy composition will change the morphology and size of γ″ and δ, which is conductive to the properties of the alloys. Hence, this project will focus on the γ″→δ transformation in the Inconel 718 alloy. Firstly, the intermediated phase transformation mechanism will be investigated by processing craft and alloy composition control, accompanied by theoretical calculation, microstructural analysis, and property measurement. The intermediated phase evolution mechanism will be accordingly clarified. Secondly, the internal relations between the processing craft/alloy composition, the intermediated phase transformation/microstructure, and the alloy property will be established based on the experiments mentioned above. The approaches of effective microstructural control will be developed, and finally this will provide new ideas for the exploitation of high property Inconel 718 alloy. The successful implementation of this project would provide significant reference for the composition and process design of the similar nickel-base superalloy.

随着航空发动机、火箭等的发展，对于目前应用最广的高温合金Inconel 718合金来说，对其高温强度提出了更高的要求。合金中γ″→δ相变机制是了解其组织稳定性以改善性能的关键，而加工过程中储存在合金中的能量或合金成分的改变，都将影响γ″相和δ相的析出动力学及γ″→δ相变。因此，工艺或成分的调控便可以有效改变γ″相和δ相的析出形貌和尺寸，这对合金的性能有十分重要的影响。据此，本项目拟针对Inconel 718合金中γ″→δ相变开展以下研究：通过加工工艺及合金成分的调控，结合理论计算与组织分析和性能测试，探究Inconel 718合金中间相转变机制，澄清中间相析出演变机理；基于此，分别建立加工工艺/合金成分，中间相转变/组织形貌，和性能之间的内在联系，探索有效的组织调控途径，并为高性能Inconel718合金的开发提供新思路。本项目的成功实施将为同类镍基合金的成分和工艺设计提供重要的参考信息。

Inconel 718合金作为目前应用最广泛的镍基高温合金之一，广泛用于燃气轮机、航空发动机、涡轮盘、叶片、螺栓、导向器、压气机盘等零部件的制造。然而当服役温度超过650°C时，合金中的γ″相会发生快速粗化并向δ相转变，这就限制了合金在更高温度服役部件中的应用。基于此，本项目针对加工工艺及合金成分调控展开了研究，对Inconel 718合金在不同加工过程中的析出相演变及相关高温力学行为进行了系统的探究；同时，通过调整Al、Ti两种强化相形成元素，研究了Al、Ti含量对改型Inconel 718高温合金析出相类型、组织形貌及稳定性的影响，探究了中间相转变机制，阐明了合金成分、加工工艺、组织形貌与性能之间的变化规律，形成了高性能Inconel 718合金开发及形貌调控指导方案。本项目的顺利实施进一步加深了Inconel 718合金中间相转变机制的理论认知，补充相变动力学理论，阐明Inconel 718 合金合金成分、加工工艺与γ″→δ相变、γ″相和δ相析出形貌演变机理以及合金性能之间的内在联系和影响机制，明确最优的合金成分及加工工艺，从而为高性能Inconel 718 合金的制备和加工提供理论指导和技术支持。