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Laser engineered net shaping (LENS™), a metal additive manufacturing process, was employed to repair internal defects in Inconel 718. The technique involves milling slot/s around defect zone and subsequently refill the cavities with a material. This study investigates the effectiveness of two slots with different geometric shapes, rectangular and trapezoidal, to repair internal cracks and understand the influence of deposition orientation on mechanical properties of the repaired components. Trapezoidal shaped cross-section showed good fusion between deposit material and the part along the sidewalls without any void inclusion. Build-direction, especially diagonal-deposition, influenced coefficient of friction and compound-wear for non-heat-treated samples.

Nano-scale Al2O3-ZrO2 eutectic ceramic structures with shapes of thin-wall and cylinder were prepared by ultrasonic-assisted laser engineered net shaping. In the preparation process, the power of ultrasonic was adjusted in real-time on the molten pool. The generation of refining grain by ultrasonic were discussed based on the principle of crystallography. Two methods to improve the fracture toughness were analyzed. The average eutectic spacing was 60–70 nm, and the fracture toughness was 7.67 MPa·m1/2.

The widely used soft-magnetic alloy, Fe-30at%Ni, has been deposited using laser engineered net shaping (LENS™). A range of laser powers and travel speeds have been studied and correlated to phase stability and magnetic properties of the alloy. Columnar grains of the metastable fcc phase are predominant for slower travel speeds, however with increasing travel speeds, a substantial volume-fraction of a bcc , possibly martensitic, phase was observed. The bcc dominated microstructures exhibit a substantially higher saturation magnetization (M s ) compared to the fcc dominated microstructures.

A novel approach to a fabrication of high strength Fe-28%Al-5%Cr-1%Nb-2%B (% at.) intermetallic alloy by using the Laser Engineered Net Shaping (LENS™) technique was presented in this paper. The results show that the deposited material was characterized by a fine, equiaxed grain structure (grain size ∼ 10 μm) in the entire volume of the sample and second-phase particles (NbB and NbB 2 ) mainly arranged in the grain boundary areas. The boride particles contribute to a significant improvement in the compressive strength.

In this study, we created an innovative ultrafine three-dimensional quasi-continuous network (3DQCN) microstructure by in-situ laser engineered net shaping (LENS) of TiB reinforced titanium matrix composites (TiB-TMCs). As a rapid solidification process, the LENS process enabled high degree of Ti grain refinement. The in-situ processed eutectic TiB aggregated at these Ti grain boundaries, forming the ultrafine 3DQCN microstructure. The microstructural characterizations of the ultrafine 3DQCN microstructure were investigated. Effects of the TiB reinforcement and the ultrafine 3DQCN microstructure on the mechanical performance of the fabricated parts were studied. The results demonstrated that the TiB-TMCs with the ultrafine 3DQCN microstructure exhibited superior mechanical properties.

In this study, niobium carbide – stainless steel 304 (SS304) metal matrix composite was processed using laser engineering net shaping (LENS). By laser bonding NbC particles with SS304, the NbC dispersed at the grain boundaries and in the lattice. XRD results showed that NbC addition caused lattice strain, which resulted in the strengthening of the matrix metal, increase hardness, and a >75% decrease in wear rate. The carbides became abrasive particles in the metal during wear, which increased the wear resistance along with the coefficient of friction (COF). Such coating approach via LENS™ could be utilized in specific locations to protect existing steel parts or be added to new ones that may be sensitive to wear degradation as opposed to treating the entire part surface.

This paper studied fabrication of Fe-Cr stainless steel parts using the novel ultrasonic vibration-assisted laser engineered net shaping (UV-A LENS) process and investigated the effects of ultrasonic vibration on the microstructures and mechanical properties. The results showed that cross-sectional morphology as well as internal microstructure of the parts were changed by applying ultrasonic vibration in LENS process. Porosity, micro-cracks, and microstructural grain size were remarkably decreased due to the actions and influences of ultrasonic vibration. In addition, mechanical properties of the parts fabricated by UV-A LENS process were significantly improved compared with that of the parts fabricated by LENS without ultrasonic vibration. These findings indicated that UV-A LENS was an effective process to generate uniform morphology and fine microstructures to improve the mechanical properties of the parts.

Titanium matrix composites (TMCs) were prepared in situ using continuous wave ytterbium doped fiber laser in order to improve the mechanical properties of titanium. In this study, 5, 10 and 15 wt% diamond powders were premixed with commercially pure titanium (CP-Ti) powder and were laser melted using laser engineered net shaping (LENS™) system. The microstructure, reaction phases and mechanical behavior were investigated to understand the influences of diamond concentration. Average cross sectional hardness of the composite increased from 348 HV to 984 HV with increase in the diamond concentration from 5 to15 wt%. Similarly, the Young’s modulus of the composite, measured using nanoindentation, increased from 169 to 629 GPa. Such high mechanical properties of laser melted composites envisage their potential for wear resistant and high temperature applications.