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The present study concerns laser surface nitriding of Ti-6Al-4V. The Ti-6Al-4V alloy was submitted a superficial treatment of pulsed laser Nd:YAG (λ=1.064 μ\m) in atmosphere of 40wt% nitrogen-60wt% argon. The samples were characterized by optical microscopy and electron scanning microscopy. The microstructure of the surface nitrided Ti-6Al-4V consists of TiN dendrites distributed in α--Ti matrix. It can be noted that there is a significant enhancement in surface roughness after surface nitriding (6.60 μm) as compared to the as received Ti-6Al-4V (0.46 μm). The microhardness of the surface is improved to 1100 VHN as compared to the 340 VHN of substrate.

This work intends to analyze the influence of the stress and temperatures used in creep mechanical tests in the types of fractures that occurred in the superalloy Inconel 718. For this, the superalloy was subjected to creep tests under the conditions 625 to 814 MPa at temperatures of 650, 675 and 700°C. After the tests, the fractured samples were cleaned on an ultrasound and subjected to microstructural analysis using the technique of scanning electron microscopy. Images were performed with different increases in order to analyze the type of fracture that occurred in the material. The elongated sample and its reduction in area were also measured in order to study the effects of different conditions used in the creep tests under material's fracture.

The objective of this work was evaluating the microstructure of the Ti-6Al-4V alloy in creep test. Yttria stabilized zirconia with a CoNiCrAlY bond coat was atmospherically plasma sprayed on substrate. Constant load creep tests were conducted with alloy in air and in nitrogen atmospheres at stress level of 319 MPa at 600°C. The microstructural analyze shows that the predominant mechanism in the test conditions was characterized by formation and coalescence of microcavities with shape and size varieties. The size and shape of dimples are governed by number and distribution of nucleated microcavities and by stress internal level present in material.

The aim of this paper is to study of oxidation effects in creep of the Ti-6Al-4V alloy, in different atmospheres (air, nitrogen and argon). The samples were treated during 24 hours at 600°C in different atmospheres The samples treated during 24 hours at 600°C and the oxidation behavior in each atmosphere was observed. The oxidation was more aggressive in air atmosphere, forming TiO2 film in the surface. The alloy was tested in creep at 600°C in argon, nitrogen and air atmospheres using 250 MPa. The behavior of creep curves shows that useful life is better in atmospheres not so oxidant.

The objective of this work was to evaluate the creep behavior of the Ti-6Al-4V alloy focusing on the determination of the experimental parameters related to the primary and secondary creep stages. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates. Constant load creep tests were conducted with Ti-6Al-4V alloy in air for coated and uncoated samples and in nitrogen atmosphere for uncoated samples at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Results indicated the creep resistance of the coated alloy was greater than uncoated in air, but nitrogen atmosphere was more efficient in oxidation protection.