Friction Stir Layer Deposition on a Cu-containing high-entropy alloy (HEA) has been performed for its suitability of the core component of nuclear materials. Excellent irradiation resistance in this Cu-containing HEA has been reported previously. Friction stir layer deposition (FSLD) offers a solid-state deformation processing route to metal additive manufacturing, in which the feed material undergoes severe plastic deformation at elevated temperatures. Some of the key advantages of this process are fabrication of fully dense material with fine, equiaxed grain structures. This work reports the detailed microstructure of the FSLD product, and it discusses the grain refinement and micro-hardness variation observed in FSLD product.

Plasma sprayed zirconium (Zr) metal coatings onto uranium-molybdenum (U-Mo) alloy nuclear reactor fuel foils act as a diffusion barrier between the fuel and the aluminum fuel cladding. Neutron diffraction was performed to investigate the crystallographic phase composition, crystal orientations and lattice parameters of the plasma sprayed Zr and the U-Mo substrate. The neutron diffraction results show that the plasma sprayed Zr coating is crystalline, phase pure (alpha-Zr) and has preferred crystalline orientation likely due to directional solidification. Also, there is a slight (~0.01 Å for a direction and ~0.016 Å for c direction) increase in the plasma sprayed Zr lattice parameter indicating oxygen in the lattice and some residual thermo-mechanical strain. There is little or no modification of the underlying U-Mo following plasma spraying. In particular, there is no detectable allotropic transformation of the starting gamma-U (body-centered cubic) to alpha-U (orthorhombic). The unique neutron diffraction capabilities at LANL are well suited for nuclear fuel characterization offering distinct advantages over conventional X-ray diffraction and destructive metallography.

Achieving appropriate temperature uniformity in a heat treat application with direct fired burners requires paying particular attention to burner type, spacing and arrangement. Selection of the appropriate burner technology is crucial for achieving required uniformity. This paper explains the importance of proper burner placement (spacing and arrangement) and will describe advancements in burner technologies that provide important options to achieve required temperature uniformity. The paper concludes with several short case studies explaining the application of spacing, arrangement and technology to achieve the proper temperature uniformity in the furnace. These case studies are relevant to thermal processing of titanium, steel, and aluminum components.

Superior characteristics of the cold sprayed coating have led to many high-tech applications. Until recently, all these applications were carried out using ‘stationary’ systems only, while some applications such as in-situ repair of aircraft body/engine parts require a portable system. Recently a ‘Portable High Pressure Cold Spray System’ called KINETIKS 2000-2 has been developed. This system is capable of 400 C/20 bars nitrogen/helium jet, and produces dense coatings with clean interfaces of many materials. In order to establish the suitability of this process for producing aluminum alloy coatings for aerospace and other high tech industries, various aluminum alloys (CP-Al, HP-Al, 6061 Al, 7005 Al) coatings were produced over many substrate materials (2024 Al, 7005 Al, 4041 Steel, ZE41A Mg). Coatings were characterized using microstructure, bond strength, bend test, corrosion studies, etc. Microstructural study showed that dense coatings with about 2-4% porosity values were produced with clean and well bonded interfaces. Bond strength of these coatings varied between 20 to 35 MPa, Bend test results showed that the coatings have adequate strengths and could withstand severe strain conditions. Salt fog corrosion studies (ASTM B 117) showed that the coatings impart corrosion resistance to the substrates.

The drive for increased efficiency and carbon reduction in next-generation boilers is pushing conventional materials to their limits in terms of strength and oxidation resistance. While traditional isothermal testing of simple coupons provides some insight into material performance, it fails to accurately represent the heat transfer conditions present in operational boilers. This paper introduces a novel test method designed to evaluate the degradation of candidate materials under more realistic heat flux conditions. The method, applied to tubular specimens using both laboratory air and steam as cooling media, demonstrates a significant impact of thermal gradients on material performance. Initial comparisons between tubular heat flux specimens and flat isothermal specimens of 15Mo3 revealed increased oxidation kinetics and altered oxide morphology under heat flux conditions. The paper details the design of this heat flux test, presents results from initial work on 15Mo3 under air and steam conditions, and includes findings from further studies on oxides formed on 2-1/4Cr material under both heat flux and isothermal conditions. This research represents a crucial step toward more accurate prediction of material behavior in next-generation boiler designs.

Intermittent opens in hand-assembled electronic components have a number of expected causes. In this case the failure mechanism that was identified is of concern in certain industries, but is unexpected in the electronics business. Solder in solder pots and in flow solder systems is expected to become contaminated with the various metals and other materials that the solder contacts during use. In the analysis presented here, the solder was determined to be contaminated with mercury. This contaminated solder caused wires tinned in the solder to fracture due to liquid-metal embrittlement. Liquid-metal embrittlement (LME) is the reduction in metal ductility caused by contact with liquid metal.

The focused ion beam system (FIB) has become a valuable tool for the preparation of transmission electron microscope (TEM) samples. Several FIB preparation techniques exist but of particular interest is the lift-out technique, which allows for the extraction of a thin membrane from a bulk material. This technique has seen great success in the preparation of cross sectional samples. We explore the use of this technique for planar sample preparation to examine grain deformation due to nanoindentation in a reference copper material.

This paper investigates a hypothesis for understanding how the substrate texture influences the adhesive strength. A surface-scale fractal analysis is carried out on measured surface textures obtained from various metallic substrate materials. The results of these area-scale analyzes are correlated with the adhesive tensile strength of the finished coating. The results show that scale-considering fractal parameters predict bond strength better than average roughness, and that they support a hypothesis that relates bond to available surface area at a given scale. Paper includes a German-language abstract.

For the adhesion of thermally sprayed coatings, the substrate roughness, or topography, plays an important role in droplet-substrate interaction. The lack of availability of methods for appropriate characterization of the real topography is a major difficulty in understanding the role that topography plays during droplet impact, wetting and solidification. The complex nature of the usually chaotic substrate topographies cannot be fully characterized by conventional roughness numbers such as Sa or Ra. In our study a scale-sensitive fractal analysis method is used for describing the morphology of grit blasted surfaces. Area-scale analyses are performed on 3D data sets acquired from different substrate materials, treated by various grit blast parameters. From fractal analysis it is known that the apparent area of a rough surface increases as the scale of observation decreases. The area-scale relations are used on one side to guide experimental design for topographical data acquisition and analysis, and on the other side to understand the influence of the grit blast process on the different kind of substrates. The potential of these scale-sensitive analysis techniques for supporting statistical correlations and clear physical interpretations will be discussed.

It is widely recognized that substrate surface roughness, or topography, plays an important role in droplet-substrate interaction and the adhesion of sprayed coatings. A key difficulty in understanding the role that topography plays during droplet impact, wetting and solidification has been the availability of methods for appropriate characterization of the topography. The complex nature of the substrate topographies cannot be adequately characterized by conventional methods such as Ra. In this work, scale-sensitive fractal analyses are considered for advancing the understanding of roughness of grit blasted surfaces in thermal spray applications. Area-scale analysis is performed on 3D data sets acquired from different grit-blasted substrates. From fractal analysis it is known that the apparent area of a rough surface increases as the scale of observation decreases. The area-scale relations are used to guide experimental design for topographical data acquisition and analysis and to better understand the influence of grit blasting on substrates for thermal spray. The potential of these scale-sensitive analysis techniques to fulfill the above bases for supporting statistical correlations and clear physical interpretations is discussed.