JOINT STUDY ON THE DEVELOPMENT OF Ni-Al-Ti BASE AUPERALLOYS

为了开发一种新型的β(NiAl：B2)基高温合金，研究了Ni-Al系中的相平衡，并根据相平衡信息进行了一些微观组织控制。主要通过扩散耦合实验确定了Ni-Al-Ti、Ni-Al-Fe、Ni-Al-Co和Ni-Al-Ti基系中β、γ(A1)、γ‘(L1_2)、β’(L21)和ETa(D0&lt；24)相之间的相平衡。对Ni-Al、Ni-Ti、Ni-Al-Ti和Ni-Al-Fe系的相图进行了热力学分析和计算机计算。2.通过显微组织控制，通过常规的形变热处理获得了多相合金。在β相发生马氏体相变的Ni-Al-Fe和Ni-Al-Co系中，三种类型的β+伽马‘结构…多相合金的力学性能(1)伽马+β两相合金的力学性能：伽马相的引入大大提高了合金的塑性，在室温下表现出良好的拉伸性能。在600ﾟC以上，高温强度随温度的升高而降低；(2)伽马+贝塔两相合金；具有片层结构的合金在室温下具有良好的力学性能。(3)γ‘+β+β’三相合金；Ni-(15-25)Al-(7-15)Ti基三相合金在700ﾟC以下表现出比某些实用高温合金更高的强度，而塑性的提高是实际应用所必需的。本研究得出结论：含β基的Ni-Al基高温合金具有足够的抗氧化性，在700ﾟ℃以下表现出比许多实用高温合金更高的强度。

To develop a new type of beta (NiAl : B2) -base superalloy, phase equilibria in the Ni-Al base systems have been investigated and some microstructural controls based on the information of the phase equilibria have been performed. The results obtained are summarized as follows.1, Phase Equilibria in the Ni-Al Base SystemsThe phase equilibria among the beta, gamma (A1), gamma' (L1_2), beta' (L2_1) and eta (D0_<24>) phases in the Ni-Al-Ti, Ni-Al-Fe, Ni-Al-Co and Ni-Al-Ti-base systems were determined mainly by diffusion couple experiment. Thermodynamic analysis and computer calculation of phase diagrams of the Ni-Al, Ni-Ti, Ni-Al-Ti, and Ni-Al-Fe systems were also carried out.2, Microstructural Controlgamma+beta, gamma'+beta and gamma+gamma'+beta multi-phase alloys were obtained by a conventional thermomechanical treatment through the microstructural control. In the Ni-Al-Fe and Ni-Al-Co systems where martensitic transformation occurs in the beta phase, three types of beta+gamma' structure … More s i.e.blocky, fine lamellar and widmanstatten structures, can be obtained.3, Mechanical Properties of Multi-Phase Alloys(1) gamma+beta two-phase alloys ; the introduction of gamma phase improves the ductility drastically and exhibits a good tensile properties at room temperature. This type of alloys shows an excellent oxidation resistance, while high-temperature strength decreases with increasing temperature over 600ﾟC.(2) gamma+beta two-phase alloys ; the alloys with the lamellar structure show an excellent mechanical properties at room temperature. The high-temperature strength is slightly higher than that of the gamma+beta two-phase alloy.(3) gamma'+beta+beta' three-phase alloys ; Ni- (15-25) Al- (7-15) Ti base three-phase alloys exhibit an excellent strength higher than that of some practical superalloys at the temperatures below 700ﾟC,while the increase in ductility is necessary for the practical use.It is concluded from the present study that the Ni-Al base superalloys with the beta matrix have sufficient oxidation resistance and exhibit strength higher than many practical superalloys at the temperatures below 700ﾟC. Less