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The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts.

An experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication.

Because of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts.

The novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.

This study aims to uncover the multiscale relations among geometry, surface finish, microstructure and fatigue properties of curved-surface AlSi10Mg parts fabricated by powder bed fusion (PBF) additive manufacturing.

This paper investigated the high-cycle tensile and bending fatigue behaviors of PBF-built AlSi10Mg parts with curved surfaces. Besides, the surface finish, porosity and microstructure around various curvatures were characterized. Meanwhile, the stress distributions of the fatigue specimens with curved surfaces under the dynamic tensile/bending loading were analyzed via theoretical analysis and ANSYS simulation.

The results showed that the as-built specimens with the smallest curvature exhibited the best surface quality, smallest grain sizes and thinnest grain boundaries. In addition, the tensile fatigue fracture occurred around the largest curvature position of fatigue specimens, which was consistent with the simulated fatigue safety factor results. Moreover, the bending fatigue specimens with the largest curvature presented the shortest fatigue life due to the highest bending and shear stresses along the loading direction.

So far, most studies have focused on the fatigue behavior of as-built AlSi10Mg parts with planar structures only. The investigation on fatigue properties of as-built AlSi10Mg parts with curved surfaces remains unexplored. This study provides new insights into the characterization and quantification of the fatigue performance of PBF-built metal parts with complex geometries, the knowledge of which can promote their adoption in real industries.