TiAl/NiCoCrAl层板复合材料的EB-PVD制备及组织性能研究

Structure and Property Research on TiAl/NiCoCrAl Multilayer Composites Fabricated by EB-PVD

采用电子束物理气相沉积(EB-PVD)技术,成功制备了尺寸为150mm×100mm×0.4mm的TiAl/NiCoCrAl层板复合材料,并对其物相组成、断口形貌和室温力学性能与TiAl单层材料进行了对比分析。结果表明,在TiAl/NiCoCrAl层板复合材料中,NiCoCrAl层主要由Ni3Al和NiCrCo组成,TiAl层由γ相、α2相和τ相组成且未发现TiAl单层材料中看到的分层现象;TiAl/NiCoCrAl层板复合材料的强度和韧性都要高于TiAl单层材料,其断裂方式由沿晶脆性断裂转变为具有一定延性的穿晶断裂和沿晶断裂的混合断裂方式。TiAl/NiCoCrAl层板复合材料的强化机制主要为细晶弥散强化;该材料的韧化机制主要为裂纹的偏转、微桥接和弯曲增韧。

TiAl/NiCoCrAl multilayer composites with 150mm 100ram 0.4mm were fabricated successfully by EB-PVD process. The phase composition, fracture morphology and mechanical properties of TiAl/NiCoCrAl multilayer composites were compared with that of one-layer TiAl alloys. The results indicate that NiCoCrAl layer of TiAl/NiCoCrAl multilayer composites mainly consist of Ni3 Al and NiCrCo, and the TiAl layer is composed of γ, α2 and τ phase, but no delamination existed in the one-layer Ti-Al alloys is found. TiAl/ NiCoCrAl multilayer composites have higher bending strength and better ductility than one-layer TiAl alloys. Compared with the TiAl- based alloys sheet, the fractures of the TiAl/NiCoCrAl multilayer composites are diverted from the manner of brittle intergranular fracture to the mixed manner of brittle intergranular fracture with some ductile transcrystalline fracture. The strengthening mechanisms of the TiAl/NiCoCrAl multilayer composites are the fine grained dispersion strengthening, and the toughening mechanisms are the crack deflection, the micro bridge join and the crack bend toughening.