Different materials have been welded by laser beam. This process allows to obtain high quality welds with lower thermal effect. Laser beam welding produces narrow and high penetration welds without filler material. However, this process modifies the mechanical and microstructural properties of the welded joints. Therefore, this is currently a research topic, mainly using Advanced High Strength Steel (AHSS). These materials are used in the automotive industry. As a result, it is important to study the thermometallurgical and mechanical behavior of welded steels. In addition, a tool used to approximate the thermal effect in the fusion zone (FZ) and heat affected zone (HAZ) has been the computational numerical simulation. In this work, two butt joints of DP600 steel plates of 200 mm x 150 mm and 2 mm thickness with different welding sequences were simulated using the SYSWELD finite element software. The results of both coupons were compared and it was determined that the distortion and residual stresses decreased in the second coupon by applying a different welding sequence with equal heat input.

The elastic constants, elastic modulus, anisotropy, Debye temperature, and sound velocity properties of Mo0.85Nb0.15B3 were investigated by first-principles calculations under pressure based on the generalized gradient approximation (GGA) proposed by Perdew–Burke-Ernzerhof (PBE). Employing the stress-strain method and the Voigt-Reuss-Hill approximations, were calculated the elastic properties of single and polycrystalline crystals; Bulk modulus (B), Young modulus (E), Poisson ratio (ν), Pugh ratio (G/B), Debye temperature and the Cauchy pressure terms. The calculated ν, Cauchy pressure, and Pugh ratio G/B values indicate that Mo0.85Nb0.15B3 shows a transition from brittle to ductile under pressure. Finally, the Density of States decreases as pressure increases.

In this research it was experimentally analyzed the effect of the parameters of the Pulsed Micro Laser Welding Process Nd:YAG on the microstructural behavior of a nickel base superalloy (IN-738). For this purpose, different laser welding tests were performed on samples subjected to different heat treatment conditions obtained from the gas turbine blades. The influence of the power and the speed welding of the applied process and heat treatment condition on the weld geometry, microstructure and mechanical properties was determined. The microstructures of the obtained welds were characterized by scanning electron microscopy and Vickers hardness tests. In general, alternatives to homogenize and rejuvenate the microstructure of the base material are proposed in order to avoid the formation and propagation of cracks. The results are discussed mainly in terms of the present phases and decomposition of carbides, which considerably affect the weldability of the IN-738 superalloy. This study provides useful information for the subsequent restoration of the 2nd step turbine blades by using of the Laser Welding Process Nd:YAG.

The work presents an electrochemical study of the corrosion behaviour of two TiC/Cu-Ni metal matrix composites with a content of 10 and 20 wt.% Ni immersed in synthetic seawater. The composites were synthesized by a capillary infiltration technique, obtaining dense materials TiC/Cu-10Ni and TiC/Cu-20 Ni with a residual porosity of 1.8 and 1.7%, respectively. The corrosion rate (CR) was evaluated from the techniques of polarization curves (PC), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Electrochemical measurements were carried out under static conditions, ambient temperature and atmospheric pressure at 24 hours exposure in the electrolytic medium. The corrosion rate is affected by the Ni content in the matrix, with less corrosion in the composite with a higher Ni content. The higher content of Ni in the Cu-Ni alloy provides higher passivation and stability to the corrosion products film that are absorbed on the composite surface. Microscopic examination (SEM) showed a characteristic morphology of a corrosion mechanism of the localized type (pits and crevices) generated by a differential aeration, where the TiC/Cu-10Ni composite showed greater degradation.

This paper addresses the chemical synthesis and characterization of a composite formed by Li2O-Al2O3-Al3Fe-Al3Fe5O12/PCL which were obtained by the process of reduction of ferric chloride (FeCl3) with lithium aluminum hydride (LiAlH4) in an open atmosphere. The goal of the development of this hybrid material was to perform a superparamagnetic material with several potential applications. The results of the characterizations by scanning electron microscopy (SEM) and vibrating sample magnetometer showed a Li2O-Al2O3-Al3Fe-Al3Fe5O12 “desert rose stone”-like morphology 3D hierarchical powders formation when particles were sintered at 850 °C. Homogeneous nanometric particles after calcination at 1100 °C were observed. X-ray diffraction analysis were performed to determine their composition. Subsequently, the superparamagnetic powders were added by dispersion in a polycaprolactone (PCL) matrix, and then, were evaluated by SEM for the observation of their morphologies. The composite material presented a polymer network with an opened structure, a well dispersion of the oxides particles into the interstices with irregular topography and reliefs.

The work focuses on the analysis of electrochemical corrosion in synthetic salt medium of the TiC/Ni-20Cr composite through the polarization curve technique at four exposure times (0, 6, 12 and 24 h). The composite was prepared by liquid infiltration of the liquid alloy into a porous body of TiC. It was found a continuous and homogeneous distribution of the reinforcing material in the interconnected matrix, having a residual porosity of 6.49 vol.%. According to the electrochemical results, in both samples the highest corrosion rate (CR) was obtained at 12 h exposure due to the rupture of the film of the corrosion products, allowing the interaction of chloride ions with the metal surface. The CR of the composite was slightly higher than that of the alloy at all exposure times, so that the presence of the reinforcing particles and the residual porosity reduce the corrosion resistance of the matrix in the composite. The mechanism of corrosion observed in the alloy and the composite was by pitting, however, the composite also presents crevice corrosion by a differential aeration cell mechanism formed between the metal matrix and the ceramic reinforcement, affected by the residual porosity as confirmed by electron microscopy examination.