Microstructure and wear behavior of AlxCo1.5CrFeNi1.5Tiy high-entropy alloys

FIZ Karlsruhe

The tribological properties of Al0.6CoCrFeNi high-entropy alloy with the σ phase precipitation at elevated temperature

Micromechanisms and mechanics of ultra-mild wear in Al-Si alloys

The iron carbide Fe7C3 exhibits two types of basic crystal structures, an orthorhombic (o-) form and a hexagonal (h-) one. First-principles calculations have been performed for the basic Fe7C3 forms and for the related ?-Fe3C cementite phase. Accurate total-energy calculations show that the stability of Fe7C3 is comparable to that of ?-Fe3C. The o-Fe7C3 phase is more stable than the hexagonal one, in contrast to recent atomistic simulations. Furthermore, the calculations also show a rather low energy for a carbon vacancy in the o structure, which implies possible C deficiency in the lattice. Both Fe7C3 phases are ferromagnetic metals. Electronic band-structure calculations show that all Fe atoms exhibit high-spin states with the majority of their 3d states being almost fully occupied. From an analysis of the structural and energetic properties, the formation of the o phase in steel treatment processes and of h form in carburization of ferrite is discussed.

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Structural, electronic, and magnetic properties of iron carbide Fe7C3 phases from first-principles theory

https://www.ipen.br/biblioteca/2009/14728.pdf

MC complex carbide in AISI M2 high-speed steel

The aim of the work was to prepare an overview about the microstructures present in high-speed steel, focused on the crystallography of the carbides. High-speed steels are currently obtained by casting, powder metallurgy and more recently spray forming. High-speed steels have a high hardness resulting from a microstructure, which consists of a steel matrix (martensite and ferrite), in which embedded carbides of different crystal structure, chemical composition, morphology and size, exist. These carbides are commonly named MxC, where M represents one or more metallic atoms. These carbides can be identified by X-ray diffraction considering M as a unique metallic atom. In this work, it is discussed, in basis of the first principles of physics crystallography, the validation of this identification when it is considered that other atoms in the structure are substitutional. Further, it is discussed some requirements for data acquisition that allows the Rietveld refinement to be applied on carbide crystallography and phase amount determination.

An Overview of the Microstructures Present in High-Speed Steel -Carbides Crystallography

Aluminium-silicon alloys have been wide accepted in the automotive, electric and aerospace industries Preferred orientation is a very common condition for metals and alloys Particularly, aluminium induces texture during the forming process The preparation of an aggregate with completely random crystal orientation is a difficult task The present work was undertaken to analyse the texture by X-ray diffraction techniques, of three spray formed hypereutectic Al-Si alloys Samples were taken from a billet of an experimental alloy (alloy 1) and were subsequently hot-rolled and cold-rolled (height reduction), 72% and 70%, respectively The other used samples, alloys 2 and 3, were taken from cylinders liners The results from the Laue camera showed texture just in the axial direction of alloy 3 The pole figures also indicated the presence of a typical low intensity deformation texture, especially for alloy 3 The spray formed microstructure, which is very fine, hinders the Al-Si texture formation during mechanical work

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Crystallographic orientation-spray formed hypereutectic aluminium-silicon alloys

The shape memory effect of stainless shape memory alloy is associated to non-thermolastic g (CFC) « e (HCP) martensitic transformation. Recent results generated by our group have demonstrated that the parent austenite grain size is an important parameter for the degree of shape recovery and also in some others properties such as yield stress, hardness and volume fraction of thermal martensite. Using EBSD, this work shows that besides the above-mentioned parameters, the number of martensite orientation variants decreases when the grain size decreases.

/pdf/o-efeito-do-tamanho-de-grao-austenitico-no-numero-de-cq2yvritbf.pdf

Marilene Morelli Serna

Papers

MC complex carbide in AISI M2 high-speed steel

An Overview of the Microstructures Present in High-Speed Steel -Carbides Crystallography

Crystallographic orientation-spray formed hypereutectic aluminium-silicon alloys

O efeito do tamanho de grão austenítico no número de orientações das variantes de martensita em ligas inoxidáveis com efeito de memória de forma

Comparison of the Kerr effect and X-ray pole figure methods for determining crystallographic texture in PrFeB magnets