Electron beam powder bed fusion of Y2O3/?-TiAl nanocomposite with balanced strength and toughness
Electron beam powder bed fusion of Y2O3/?-TiAl nanocomposite with balanced strength and toughness
复制标题
强韧性平衡的Y2O3/?-TiAl纳米复合材料的电子束粉末床熔合
DOI：
10.1016/j.addma.2023.103650
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发表时间：
2023
影响因子：
11
通讯作者：
Gao B
中科院分区：
文献类型：
--
作者：
Gao B
本文报道了采用多点熔融策略结合较小的层厚增材制备Y2 O3/γ-TiAl纳米复合材料。与孵化熔融相比，多点熔融策略导致更低的γ和B2-相的分数，更小的片层间距为208 ± 72 nm，α2/γ之间具有平直界面，并且纳米颗粒均匀分布，具有更细的尺寸为90 ± 38 nm。孪晶可以在等轴γ晶粒和γ层内形成;这适用于多点和孵化熔体样品。γ层中的孪晶可以穿过孪晶界面传播，但终止于γ/α 2界面。在800 ℃时，该钢的抗拉强度为556 ± 11 MPa，塑性为17.0 ± 3.1%，室温断裂韧性为16.5 ± 0.3 MPa. m。定量显微镜检查证实了多点样品在x-y平面内的均匀微观结构，同时使用较小的层厚度有助于减少由于热循环引起的微观结构退化。对于Y2 O3纳米颗粒，透射电子显微镜（TEM）观察到了单斜晶系的棒状Y2 O3和立方晶系的近球形Y2 O3。高分辨透射电子显微镜（TEM）分析表明，Y2 O3/TiAl界面清洁，无界面反应，呈半共格或共格结合，结合较强。
This paper reports the use of multi-spot melt strategy coupled with smaller layer thickness to additively manufacture Y2O3/γ-TiAl nanocomposite. In contrast to the hatch melt, the multi-spot melt strategy results in a lower fraction of γ and B2-phase, a smaller lamellar spacing of 208 ± 72 nm with straight interface between α2/γ, and a uniformly distributed nanoparticles with a finer size of 90 ± 38 nm. Twins can form in the equiaxed γ grains and within γ lamellae; this applies to both the multi-spot and hatch melt samples. Twins within the γ lamellae can propagate across the twin interface but terminate at the γ/α2interface. A good combination of 556 ± 11 MPa (tensile strength) and 17.0 ± 3.1 % (ductility) at 800 ℃ with 16.5 ± 0.3 MPa√m (room-temperature fracture toughness) is achieved in the as-built condition. Quantitative microscopy confirms a homogeneous microstructure within the x-y plane for the multi-spot sample, whilst the use of smaller layer thickness helps to reduce the microstructure degradation due to thermal cycling. In terms of the Y2O3nanoparticles, both the rod-like Y2O3with monoclinic and the near spherical Y2O3with cubic crystal system are identified using transmission electron microscopy (TEM). High-resolution TEM reveals that the Y2O3/TiAl interface is clean, free of interfacial reactions, and with a semi-coherent or coherent type, suggesting a strong bonding.