1 Erratum to: METALLURGICAL AND MATERIALS TRANSACTIONS A, VOLUME 47A, DECEMBER 2016, pp. 5685-5690 DOI 10.1007/s11661-016-3755-5In the original article Jeongyong Choi’s given name is misspelled. It is corrected as shown in this erratum.

This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

Cross-sectional microstructural analyses of micron/nano-sized structures (termed microneedles) formed by low and high fluence pulse laser ablation of AISI 4340 steel, Ti6Al4V, and Al 5754 alloy specimens were performed. Dependence of length scale and orientation of microneedle microstructures on energy absorptance during laser irradiation, heat transfer direction, absorptivity, and thermal conductivity of the material was established. Microneedle nucleation and growth process were explained based on penetration depths, redeposition of ablated material, and ablation rates.

Yttria-stabilized zirconia (YSZ) films are of considerable interest in optical, electronic and aerospace community and multitude of fabrication techniques are reported in the literature. This paper reports the characteristics of the YSZ films produced by pulsed laser deposition technique using a KrF excimer laser with yttria-stabilized zirconia targets. Morphological characteristics of the YSZ films were investigated by atomic force microscope (AFM) and scanning electron microscope. Distinct peak and valley structures with height differences in the range of 10–30 nm were observed in AFM images of the YSZ film surfaces, and measured roughness was 3.5–6.5 nm. A nanoindenter was used to investigate mechanical properties of the films deposited at different chamber pressure. Measured hardness and Young's modulus were about 10–11 GPa and 86–95 GPa respectively. Elemental composition and structural characteristics of the YSZ films were analyzed by electron prove micro-analyzer and X-ray diffraction, respectively.

The direct metal deposition (DMD) process is drawing considerable contemporary interest due to its capability to deliver “Art to Part”. DMD can reduce the lead time for a concept to product by eliminating several intermediate steps. The most attractive feature of the process is that not only can it produce functional parts but it can also be interfaced with the homogenization design method, heterogeneous solid model and computer aided design software to produce “Designed Material” with desired properties generally not observed in nature. Closed loop DMD is a synthesis of multiple technologies including lasers, sensors, computer numerical controlled work handling stage, CAD/CAM software and cladding metallurgy. This paper describes the methodology used to produce a designed macro- and microstructure and reviews the state of the art for closed loop DMD.

Although, additive Manufacturing (AM) has been hailed as the “third industrial revolution” by The Economist magazine [April-2012], the first patent on Stereo-lithography was awarded in 1986. An enabling technology which can build, repair or reconfigure components layer by layer or even pixel by pixel with appropriate materials to match the performance will enhance the productivity thus reduce energy consumption. Innovative product such a metallic composites with negative co-efficient of thermal expansion has already been demonstrated. The capability to form a three-dimensional object directly form digital data reduces many intermediate steps in manufacturing and, therefore, potentially an attractive and economic fabrication method. This is very suitable for low volume manufacturing.The major challenge for design of additive manufacturing machine is on line “Quality assurance” due to its application in low volume manufacturing. Statistical quality control is not applicable due to low volume. Moreover, any new innovative product has to go thorough a long process of certification before adaptation, especially for Aerospace and medical device industry.This paper presents the design methodology for Smart Metallic Additive Manufacturing System (s-AMS). In-situ optical diagnostics and its capability to integrate with the process control is a prudent alternative. The two main groups of AM are powder bed (e.g. Laser Sintering) and pneumatically delivered powder (e.g. Direct Metal Deposition [DMD]) to fabricate components. DMD enables one to deposit different material at different pixels with a given height directly from a CAD drawing. The feed back loop also controls the thermal cycle. New optical Sensors are being developed to control product health and geometry using imaging, cooling rate by monitoring temperature, microstructure and composition using optical spectra. Ultimately these sensors will enable one to “Certify as you Build”. Recently the author and his group have developed a technique to analyze the plasma spectra to predict the solid-state phase transformation, which opens up the new horizon for the materials processing and manufacturing. Flexibility of the process is enormous and essentially it is an enabling technology to materialize many a design. Conceptually one can seat in Houston and fabricate in Haifa. This paper discusses the in-situ diagnostic methods and its integration in the design of the machine.