다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

In this work, results of {\it ab-initio} band structure calculations for $A_2BC$ Heusler compounds that have $A$ and $B$ sites occupied by transition metals and $C$ by a main group element are presented. This class of materials includes some interesting half-metallic and ferromagnetic properties. The calculations have been performed in order to understand the properties of the minority band gap and the peculiar magnetic behavior found in these materials. Among the interesting aspects of the electronic structure of the materials are the contributions from both $A$ and $B$ atoms to states near the Fermi energy and to the total magnetic moment. The magnitude of the total magnetic moment, which depends as well on the kind of $C$ atoms, shows a trend consistent with the Slater-Pauling type behavior in several classes of these compounds. The localized moment in these magnetic compounds resides at the $B$ site. Other than in the classical Cu$_2$-based Heusler compounds, the $A$ atoms in Co$_2$, Fe$_2$, and Mn$_2$ based compounds may contribute pronounced to the total magnetic moment.

Calculated electronic and magnetic properties of the half-metallic, transition metal based Heusler compounds

In this paper, results of ab initio band structure calculations for A2BC Heusler compounds that have A and B sites occupied by transition metals and C by a main group element are presented. This class of materials includes some interesting half-metallic and ferromagnetic properties. The calculations have been performed in order to understand the properties of the minority band gap, the peculiar transport properties and magnetic behaviour found in these materials. Among the interesting aspects of the electronic structure of the materials are the contributions from both A and B atoms to the total magnetic moment. The magnitude of the total magnetic moment shows a trend consistent with the Slater–Pauling type behaviour in several classes of these compounds. The total magnetic moment also depends on the kind of C atoms although they do not directly contribute to it. In Co2 compounds, a change of the C element changes the contribution of the t2g states to the moment at the Co sites. The localized moment in these magnetic compounds resides at the B site. Other than in the classical Cu2-based Heusler compounds, the A atoms in Co2, Fe2 and Mn2-based compounds may contribute significantly to the total magnetic moment. It is shown that the inclusion of electron–electron correlation in the form of LDA + U calculations helps to understand the magnetic properties of those compounds that already exhibit a minority gap in calculations where it is neglected. Besides the large group of Co2 compounds, half-metallic ferromagnetism was here found only in such compounds that contain Mn.

https://iopscience.iop.org/article/10.1088/0022-3727/40/6/S01/pdf

Friction stir welding/processing of metals and alloys: A comprehensive review on microstructural evolution

Recent progress on control strategies for inherent issues in friction stir welding

Surface composites by friction stir processing: A review

Effect of carbides on embrittlement of Fe3Al based intermetallic alloys

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Structure and properties of Fe–Al–Ti intermetallic alloys

The effect of carbon content (0.013 to 0.50 wt%C) on structure and mechanical properties of electroslag remelted iron aluminides based on Fe3Al containing approximately 16 wt% (28 at%) aluminium alloy has been studied. At low carbon contents (0.031 wt% or less) the ESR ingots suffer from hydrogen embrittlement which results in poor mechanical properties. At high (0.074 wt% or more) carbon contents the hardness and strength of ESR ingots increase with increasing carbon content without significant change in ductility. This is attributed to the solid solution strengthening arising from interstitial carbon present in the Fe3Al matrix as well as to the increased amount of Fe3AlC (perovskite) precipitation. The mechanical properties of these high carbon ESR cast alloys are comparable or superior to those reported for high purity wrought alloys with similar aluminium contents. The machinability of ESR ingots improves with increase in carbon content. This is attributed to the presence of uniformly distributed Fe3AlC precipitates in the ingots which allow formation of small and uniform size chips during machining.

Ujjwal Prakash

Papers

Surface composites by friction stir processing: A review

Effect of carbides on embrittlement of Fe3Al based intermetallic alloys

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Structure and properties of Fe–Al–Ti intermetallic alloys

Effect of carbon content on mechanical properties of electroslag remelted Fe3Al based intermetallic alloys