Abstract The influence of a unique layered microstructure consisting of duplex-like region and equiaxed γ grain layers (γ bands) on the fatigue properties of Ti-48Al-2Cr-2Nb alloy bars fabricated by electron beam melting (EBM) was investigated at room temperature (RT) and 1023 K focusing on the angle (θ) between the building direction and cylinder (loading) axis. We found for the first time the fatigue strengths of the alloy bars with the layered microstructure depend strongly on the angle θ. Particularly, the fatigue strength of the alloy bars fabricated at θ = 45° is comparable to that of the hot isostatic pressing (HIP) treated cast alloys, even without HIP treatment. We also found the alloy bars fabricated at θ = 0° and 45° exhibit high fatigue strengths in the low-cycle fatigue life region at 1023 K similar to θ = 45° alloy bars at RT. These high fatigue strengths are caused by inhibition of the brittle main crack initiation by stress relaxation due to shear deformation at the γ bands and large plasticity of the alloys. These findings indicate that the alloys fabricated by EBM at θ = 45° with the unique layered microstructure have a great potential for aerospace and automobile applications.

中文翻译：

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独特的层状组织对电子束熔炼Ti-48Al-2Cr-2Nb合金疲劳性能的影响

摘要 研究了由类双相区和等轴γ晶粒层（γ带）组成的独特层状组织对电子束熔炼（EBM）法制备的Ti-48Al-2Cr-2Nb合金棒材在室温下疲劳性能的影响。 (RT) 和 1023 K 聚焦于建筑方向和圆柱体（载荷）轴之间的角度 (θ)。我们首次发现具有层状显微组织的合金棒材的疲劳强度强烈依赖于角度 θ。特别是，在 θ = 45° 下制造的合金棒的疲劳强度与热等静压 (HIP) 处理的铸造合金相当，即使没有 HIP 处理。我们还发现在 θ = 0° 和 45° 下制造的合金棒在 1023 K 的低周疲劳寿命区域表现出高疲劳强度，类似于 θ = 45° 在 RT 下的合金棒。这些高疲劳强度是由于 γ 带处的剪切变形和合金的大塑性引起的应力松弛抑制了脆性主裂纹萌生造成的。这些发现表明，通过 EBM 在 θ = 45° 下制造的具有独特层状微观结构的合金在航空航天和汽车应用方面具有巨大的潜力。