Chapters authored
Brazing Behaviour of Ag-Cu Filler Materials
Ecological brazing rods (cadmium free) represent a technical solution particularly useful for joining metallic or non-metallic components, providing the required mechanical and functional characteristics obtained in reproducible manufacturing conditions and at reasonable costs. The new class of coated rods for brazing must provide high deposition efficiency, chemical compatibility in relation to a number of metals and alloys currently used in industry and high corrosion resistance in different media. Such diverse characteristics can be obtained by achieving a special coating that contains a mixture of materials having a role of chemical activation and catalyst effects, as well as contributing to increasing the adherence to unmolten interfaces. This chapter presents some results obtained by using experimental brazing filler materials for different types of materials and applications. There are briefly highlighted some aspects on the diffusion effects of chemical elements in the soldering interface, the bonding of ceramics and some issues related to the effects of chemical elements from the brazing material.
Part of the book: Soldering Materials
Characterization and Testing of High-Entropy Alloys from AlCrFeCoNi System for Military Applications
High-entropy alloys (HEAs) can be obtained using various metallurgical processes such as vacuum arc remelting (VAR), induction melting, powder metallurgy, additive manufacturing, plasma sintering of powders, etc. Among these methods, the obtaining process in the VAR plant provides superior homogeneity characteristics for metal matrices, simultaneously with advanced purity, due to the high level of protection of the melts. The chapter presents a series of results on alloys with high entropy from the AlCrFeCoNi system, which can be used for various applications, including in the military field, for the realization of high-speed penetration protection panels. Experimental alloys were obtained by melting in electric arc under an argon atmosphere, using high-purity raw materials (greater than 99.5 wt%), and homogenization is ensured by successive five-times remelting of mini-ingots. The obtained alloys were subjected to microstructural analyses, mechanical tests, and also dynamic impact tests using incendiary perforation projectiles. At the same time, some tests were carried out on ballistic packages made of different materials, including high-entropy alloys. The results obtained in mechanical tests revealed high values of microhardness (over 600 HV0.1) as well as compressive strengths above 2000 MPa. The mechanical characteristics of these alloys can undergo substantial changes by applying several heat treatments.
Part of the book: Engineering Steels and High Entropy-Alloys
High Entropy Alloys for Medical Applications
A wide variety of metallic biomaterials have been developed so far, including various types of alloys. However, there is a strong need in the medical field for new solutions in what concerns metallic biomaterials with superior biocompatibility and mechanical properties in order to meet future requirements, including the recently developed high entropy alloys (HEAs). This chapter presents some characteristics of high entropy biocompatible metallic alloys produced in an electric-arc remelting furnace in argon inert atmosphere. The effects of the chemical elements used, the microstructural features, and some mechanical characteristics, both in the cast state or after some heat treatments, are highlighted.
Part of the book: Engineering Steels and High Entropy-Alloys