Alloy Design and Microstructural Control in Ni-based Multi-Intermetallic In-situ Composite Materials

采用Ni_3Al-Ni_3Nb-Ni_3Ti、Ni_3Al-Ni_3Ti-Ni_3V、Ni_3Al-Ni_3Nb-Ni_3V和Ni_3Si-Ni_3Nb-Ni_3Ti伪三元合金体系，从合金设计和显微组织控制等方面研究了多金属间化合物原位复合材料作为新型高温结构材料的候选材料。从本研究中得到以下结果。(1)在Ni_3Al-Ni_3Ti-Ni_3V和Ni_3Al-Ni_3Nb-Ni_3V伪三元合金体系中形成了由L1_2和D0_<22>相组成的双多相组织，其显微组织极其精细，上下多相组织之间以及组成相之间均具有高度共格的界面结构。(2)在Ni_3Si-Ni_3Nb-Ni_3Ti伪三元合金体系中，由于l12和d0 <24>两组分相的溶解度随温度变化而发生析出现象，因此析出强化适用于该合金体系。(3) Ni_3Al-Ni_3Ti-Ni_3V和Ni_3Al-Ni_3Nb-Ni_3V伪三元合金的流动强度与温度呈正相关，高温强度极高，在较宽的温度范围内具有合理的拉伸延展性。蠕变速率和蠕变断裂寿命与大多数高温合金或高级高温合金相同或优于后者。(4)对于Ni_3Al-Ni_3Ti-Ni_3V伪三元合金，可采用传统的熔融、热锻和单向凝固工艺，实现大批量生产、可靠性和低成本。(5)所研制的多金属间化合物原位复合材料作为新型高温结构材料具有广阔的应用前景。

Using Ni_3Al-Ni_3Nb-Ni_3Ti, Ni_3Al-Ni_3Ti-Ni_3V, Ni_3Al-Ni_3Nb-Ni_3V and Ni_3Si-Ni_3Nb-Ni_3Ti pseudo-ternary alloy systems, the development of multi-intermetallic in-situ composite materials as a candidate of new high-temperature structural materials was performed on alloy design and microstructure control. The following results were obtained from the present study.(1)It was found dual multi-phase microstructure composed of L1_2 and D0_<22> phases was developed in Ni_3Al-Ni_3Ti-Ni_3V and Ni_3Al-Ni_3Nb-Ni_3V pseudo-ternary alloy systems, and had extremely fine microstructure and highly coherent interface structures not only between the upper- and lower-multi-phase microstructures but also between the constituent phases.(2)In Ni_3Si-Ni_3Nb-Ni_3Ti pseudo-ternary alloy system, the precipitation phenomenon due to the solubility change by temperature between two constituent phases, L1_2 and D0_<24> was found to occur and consequently the precipitation strengthening was applicable to the present alloy system.(3)The Ni_3Al-Ni_3Ti-Ni_3V and Ni_3Al-Ni_3Nb-Ni_3V pseudo-ternary alloys displayed the positive temperature dependence of the flow strength and also extremely high high-temperature strength accompanied with reasonable tensile ductility over a wide range of temperatures. In addition, the creep rate and creep rupture life were identical to or superior to those of the most superalloys or advanced superalloys.(4)For the Ni_3Al-Ni_3Ti-Ni_3V pseudo-ternary alloys, fabrication process such as conventional melting, hot-forging and unidirectional solidification processes were found to be applicable, consequently resulting in the mass production, reliability and low-cost.(5)It was shown that the developed multi-intermetallic in-situ composite materials are strongly promising as new high-temperature structural materials.