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

Heterostructured materials have been reported as a new class of materials with superior mechanical properties, which was attributed to the development of back stress. There are numerous reports on ...

https://tandfonline.com/doi/pdf/10.1080/21663831.2019.1616331

Perspective on hetero-deformation induced (HDI) hardening and back stress

United States. Dept. of Energy. Office of Basic Energy Sciences (Energy Frontiers Research Center. Award 2008LANL1026)

Design of Radiation Tolerant Materials Via Interface Engineering

An overview of tailoring strain delocalization for strength-ductility synergy

The quick-emerging paradigm of additive manufacturing technology has revealed salient advantages in enabling the tailored-design of structural components with more exceptional performances over ordinary subtractive processing routines. As a peculiar feature, sub-micro cellular structures widely exist in additively manufactured (AM) metallic materials. This phenomenon primarily appears with high-density dislocations and segregated elements or precipitates at the cellular boundaries. The discovery of novel metastable substructures in various alloys through numerous investigations has proven their substantial effects on the engineering properties of AM components. This paper reviews the most recent research momentum regarding the formation mechanisms (elemental segregation, dislocation cell and oxide inclusion), the kinetics of the size and morphology, the growth orientation and the thermodynamic stability of these cellular structures by taking AM austenitic stainless steel as an exemplary material. Another topic of concern here is the inherent correlation between the unique cellular microstructure and the corresponding mechanical properties (strength, ductility, fatigue, etc.) and corrosion responses (passivity, irradiation damage, hydrogen embrittlement, etc.) for this category of AM materials. The design, control, and optimization of cellular structures for additive manufacturing techniques are expected to inspire new strategies for advancing high-performance structural alloy development.

About metastable cellular structure in additively manufactured austenitic stainless steels

Strain-rate dependent deformation mechanism of graphene-Al nanolaminated composites studied using micro-pillar compression

Enhanced dislocation obstruction in nanolaminated graphene/Cu composite as revealed by stress relaxation experiments

Strengthening and deformation mechanisms in nanolaminated graphene-Al composite micro-pillars affected by graphene in-plane sizes

Owing to its distinguished mechanical stiffness and strength, graphene has become an ideal reinforcing material in kinds of composite materials. In this work, the graphene (reduced graphene oxide) reinforced aluminum (Al) matrix composites were fabricated by flaky powder metallurgy. Tensile tests of pure Al matrix and graphene/Al composites with bioinspired layered structures are conducted. By means of an independently developed Python-based structural modeling program, three-dimensional microscopic structural models of graphene/Al composites can be established, in which the size, shape, orientation, location and content of graphene can be reconstructed in line with the actual graphene/Al composite structures. Elastoplastic mechanical properties, damaged materials behaviors, graphene-Al interfacial behaviors and reasonable boundary conditions are introduced and applied to perform the simulations. Based on the experimental and numerical tensile behaviors of graphene/Al composites, the effects of graphene morphology, graphene-Al interface, composite configuration and failure behavior within the tensile mechanical deformations of graphene/Al composites can be revealed and indicated, respectively. From the analysis above, a good understanding can be brought to light for the deformation mechanism of graphene/Al composites.

/pdf/composite-structural-modeling-and-tensile-mechanical-20hyji990g.pdf

Composite structural modeling and tensile mechanical behavior of graphene reinforced metal matrix composites

The strength of nanocrystalline and nanotwinned metals stops increasing or even starts decreasing when their grain size or twin thickness is below a critical size-a phenomenon known as Hall-Petch breakdown-which hinders the attainment of ultrahigh strength. Here, we report continuous strengthening in nanotwinned pure Ni with twin thicknesses ranging from 81.0 to 2.9 nm. An unprecedented strength of 4.0 GPa was achieved at extremely fine twin thickness of 2.9 nm, which is about 12 times stronger than that of conventional coarse-grained nickel. This ultrahigh strength arises from the excellent stability of twin boundaries and their strong impedance to dislocation motion. In particular, we find that secondary nanotwins are activated to sustain plastic deformation, which also contribute to the high strength. These results not only advance the understanding of the strengthening mechanisms in nanotwinned metals but also offer an alternative pathway to develop engineering materials with ultrahigh strength.

Lei Zhao

Papers

Strain-rate dependent deformation mechanism of graphene-Al nanolaminated composites studied using micro-pillar compression

Enhanced dislocation obstruction in nanolaminated graphene/Cu composite as revealed by stress relaxation experiments

Strengthening and deformation mechanisms in nanolaminated graphene-Al composite micro-pillars affected by graphene in-plane sizes

Composite structural modeling and tensile mechanical behavior of graphene reinforced metal matrix composites

Ultrastrong nanotwinned pure nickel with extremely fine twin thickness.