Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.

The scope of the paper is to investigate analytically and determine experimentally the shear resistance of low height reinforced precast concrete lintels. The chosen procedures included in national and international standards applied for the design of structural concrete elements to an estimation of shear behaviour of reinforced concrete elements are described. The characteristic and designed shear strength of precast concrete lintels are determined and compared with experimentally obtained results. The shear resistance for precast concrete lintels was determined by laboratory tests according to a European standard. The assessment of the in-situ compressive strength of concrete in precast concrete lintel is specified. The designed compressive strength class is confirmed. The real reinforcement distribution is verified to assess the wide scatter of experimentally obtained failure forces. A short literature outlook of the papers concerning investigations on lintels and shear resistance of concrete is given also. The paper can provide scientists, engineers, and designers a theoretical and experimental basis in the field of precast concrete lintels shear resistance.

Fe-based bulk metallic glasses (BMGs) have been extensively investigated due to their ultrahigh strength and elastic moduli as well as desire magnetic properties. However, these BMGs have few applications in industrial productions because of their brittleness at room temperature. This study is focused on the effect of cooling rate on the mechanical properties (especially toughness) in the Fe41Co7Cr15Mo14Y2C15B6 BMG. For this aim, two samples with the mentioned composition were fabricated in a water-cooled copper mold with a diameter of 2 mm, and in a graphite mold with a diameter of 3 mm. The formation of crystalline phases of Fe23(B, C)6, α-Fe and Mo3Co3C based on XRD patterns was observed after the partial crystallization process. To determine the toughness of the as-cast and annealed samples, the indentation technique was used. These results revealed that the maximum hardness and toughness were depicted in the sample casted in the water-cooled copper mold and annealed up to 928°C. The reason of it can be attributed to the formation of crystalline clusters in the amorphous matrix of the samples casted in the graphite mold, so that this decrease in the cooling rate causes to changing the chemical composition of the amorphous matrix.