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The microporous structure of granular soils that provides important information such as shear strength, compressibility, and hydraulic conductivity, is directly influenced by the void ratio. Therefore, a quick identification of the void ratio, by a non-destructively way and in situ becomes an interesting practice. Ultrasound has been successfully used for ceramic materials, wood, concrete and rocks. When dealing with soils, great efforts are made to understand its behavior and characteristics through wave propagation velocity. However, does still have a lack of discussions about the ultrasonic wave properties. In this paper, a study analysing 156 saturated samples of sands by ultrasound for 3 median particle size, with void ratio ranging from 0.5 to 1.1. The ultrasonic wave measurement was performed using the transmit and receiveand technique, with 50 kHz transducers. The study demonstrates a possibility of identifying transition zones between sample’s materials composition. Considering the same dominant medium, a correlation was observed among the void ratio and the maximum amplitude, the damping coefficient, dominant frequency and ultrasonic pulse speed. There is also the identification of characteristic frequencies for these media. Therefore, the novelties of the present study are mainly the development of a feasible technique to investigate void ratio of granular saturated soils using direct measurements of the ultrasonic wave characteristics.

Reducing pollutant emissions and improving safety standards are primary targets for modern mobility improvement. To meet these needs, the development of low-density steels containing aluminum is a new frontier of research for automotive applications. Low-density Fe-Mn-Al-C alloys are promising. In this regard, an alloy with high aluminum content and niobium addition belonging to the Fe-Mn-Al-C system was evaluated to understand the possible phase transformations and thus obtain a transformation diagram by continuous cooling to help future processing. Dilatometry tests were performed in a Gleeble thermomechanical simulator with different cooling rates (1, 3, 5, 10, 15, 20, 30, and 50 °C/s). Chemical analyses carried out simultaneously with dilatometry tests showed the presence of proeutectoid ferrite (αp), δ-ferrite, retained austenite, and niobium carbide (NbC). In the case of low cooling rates (1 and 3 °C/s), lamellar colonies of the eutectoid microconstituents were observed with a combination of α-ferrite and k-carbide. For higher cooling rates (5 to 50 °C/s), martensite was observed with body-centered cubic (BCC) and body-centered tetragonal (BCT) structures.

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