The aluminum alloy Al7075 is commonly used in aircraft industry due to its high mechanical resistance to weight ratio. Nevertheless when the structure is being serviced upon the severe environmental conditions or loads degradation mechanisms could often been found in the material. To improve its behavior the cold spray process with various titanium powders (e.g. CP Ti, Ti-64) deposited onto Al7075 was investigated. The spraying of angular titanium powder was performed in the presence of nitrogen and helium supplied at process parameters (temperature, pressure), which were the maximum values attainable by the CS system used. The deposits were sprayed while maintaining a standoff distance in the range from 20 to 100 mm increased by 10 mm. The experimental data indicated that the deposition efficiency had increased significantly with increasing standoff distance. The coating porosity first decreased to minimum 0.6% and then increased significantly to 9.8%. The mechanical properties of the coatings reached the highest values when the porosity was minimum. No new phases were reported in the cold sprayed titanium coatings when compared with the starting feedstock. The same process parameters were transferred to Ti6Al-4V coral like powder deposition process. The shear strength between Ti coating material and Al7075 substrate was measured. Additionally the tensile strength of the deposit only, previously disintegrated from the substrate, was checked out. The data obtained indicate that the consolidation of Ti powder with Al7075 substrate made by cold spray could be served for both: materials integration and building a component by materials disintegration, where Al substrate is removed on spraying and machining; and simply used as a technological support for additive manufacturing of a self-standing real life component.
Selective Laser Melting is a technology that can be used with various materials including aluminum alloys. The most common and suitable for SLM are AlSi10Mg and AlSi12Mg. Scalmalloy is a innovative material that can be used as high-strength alternative for the mentioned materials. Aluminum alloys are also widely utilize in aircraft production. Selective Laser Melting technology with an appropriate material can be used as substitute of traditional casting or forging technology. Thanks to good mechanical properties and printability of Scalmalloy it can be easily used for this purpose. The proposed paper consists for part which covers fundamental knowledge about AM industry, technology basics and general description of SLM. Technology capabilities with particular emphasis on most part quality influential areas are shown. Second part covers results from mechanical testing. Results from static tests are presented as well as results from quality control reports. According to authors experience the best quality control procedures are shown. Within third section technology substitution for certain parts is presented taking into account part quality, strength, good printability and costs. For some parts non-destructive and destructive tests results were demonstrated.
The modeling of energy elastic effects in polymeric liquids is discussed. Since the conformational energy depends on local degrees of freedom, we advocate the use of a local structural variable in addition to the commonly employed conformation tensor. Using a toy model that is described by rotational isomeric states and vibrations around them, the benefit of the local structural variable is illustrated when calculating the generalized canonical partition function. In order to describe nonisothermal rheology, a thermodynamically admissible set of time evolution equations is derived for the microstructure in terms of the slow tensor variable and the fast scalar variable, with the following main results. First, the temperature-like quantity appearing in the driving force for the heat flux can be directly related to the Lagrange multiplier of the energy in the generalized canonical partition function. Second, the driving forces for the structural relaxations are not given by the derivatives of the Helmholtz free energy density, but in general it is rather combinations of the derivatives of the energy and entropy densities that are relevant. And third, the exchange between local and conformational contributions to the energy, and entropy, respectively, are discussed. KEY ASPECTSEntropy elasticity of rubbers serves as a starting point for most of the current models to describe the flow of polymeric hquids with an internal conformation tensor, while consideration of energetic effects is scarce. Although, in polymeric systems, the slowest degrees of freedom are the most relevant for describing the rheology under low and moderate deformation rates, fast local degrees of freedom are required to capture the conformational energy. Recent computer simulations underline the relevance of the energetic effects particularly at strong deformations [1,2]. Conclusively, we advocate in this contribution to use a scalar local conformational variable A in addition to the commonly employed conformation tensor c. To simphfy the discussion, it is assumed that there are no structural variables with time scales intermediate between the scalar and the tensorial variables. The full details of the treatment can be found elsewhere [3]. In the following, the most important points are summarized.The benefit of using a local scalar variable for the description of conformational energetic effects is illustrated by studying a toy model in a generalized canonical ensemble. Particularly, a polyethylene-like chain is considered, the conformations of which can be described by rotational isomeric states (RIS) and vibrations around them. In order to represent the distortion effect of the flow on a polymer chain, one introduces Lagrange multipliers a,-conjugate to the structural variables Xi, which leads to the generalized canonical partition function of the form [4] PSwhere H is the energy, /3 the corresponding Lagrange multipher, and the summation (integration) runs over all of phase space (PS). Based on that partition function, expressions for the entro...
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