α-Fe中〈110〉倾斜晶界的分子动力学研究

采用分子动力学结合不同原子间相互作用势函数研究了α-Fe中具有不同位相差(26°～140°)的〈110〉倾斜晶界的强度、γ面及滑移系,并通过模拟准静态拉伸试验研究了各晶界解理断裂过程。研究结果表明,随着位相差的增加,晶界能量在110°附近出现极小值,Σ3{112}晶界是α-Fe〈110〉倾斜晶界中最稳定的晶界之一;Σ3{111}晶界解理断裂能量计算结果与实验和第一性原理计算结果符合得很好;Σ3{112}晶界解理断裂过程中伴随着孪生与滑移,从而导致其解理断裂能量高于晶界形成能。

Theoretical models for irradiation hardening and embrittlement in nuclear structural materials:a review and perspective

The study of irradiation hardening and embrittlement is critically important for the development of next-generation structural materials tolerant to neutron irradiation,and could dramatically affect the approach to the design of components for advanced nuclear reactors.In addition,a growing interest is observed in the field of research and development of irradiation-resistant materials.This review aims to provide an overview of the theoretical development related to irradiation hardening and embrittlement at moderate irradiation conditions achieved in recent years,which can help extend our fundamental knowledge on nuclear structural materials.After a general introduction to the irradiation effects on metallic materials,recent research progress covering theoretical modelling is summarized for different types of structural materials.The fundamental mechanisms are elucidated within a wide range of temporal and spatial scales.This review closes with the current understanding of irradiation hardening and embrittlement,and puts some perspectives deserving further study.

Development of Sustainable Solutions for Zebra Mussel Control Through Chemical Product Engineering

The zebra mussel is an important aquatic pest that causes great damage to freshwater-dependent industries, due to biofouling. The main goal of the project discussed here is to develop improved solutions to control this species. Three approaches have been explored in an attempt to design innovative application strategies for existing biocides： （i） encapsulation of toxins; （ii） combination of toxins; （iii） investigation of the seasonal variation of the species＇ tolerance to toxins. In this paper, the principles behind these approaches and the major results on each topic are presented. The benefits of adopting a chemical product engineering approach in conducting this project are also discussed.

Neutron irradiation effects on mechanical properties of ITER specification tungsten

In this contribution,we present the results of recent neutron irradiation campaign performed in the material test reactor BR2(Belgium)on pure tungsten.We have applied various irradiation conditions and sample geometry to assess the effect of neu-tron irradiation on hardness,bending,tensile and fracture mechanical properties.The investigated material is a commercially pure tungsten plate fabricated according to the international thermonuclear experimental reactor(ITER)specification for the application in the divertor plasma-facing components.The neutron irradiation covers a large span of temperatures and damage doses,ranging from 600 to 1200°C and 0.1-1 dpa.The obtained mechanical properties were analyzed to deduce the shift of the ductile to brittle transition temperature(DBTT)applying bending,tensile and fracture toughness-testing procedures.Then,a correlation of the fracture toughness with the change of the hardness was established.The obtained results are compared with the already published results on another ITER specification grade produced in the form of a rod.The presented and discussed results show that the performance of the compared grades in terms of the irradiation-induced embrittlement is similar,and that the irradiation in the high-temperature region(600-800°C)causes a considerable DBTT shift already at 0.2-0.5 dpa.

Mechanical properties of Fe-rich Si alloy from Hamiltonian

The physical origins of the mechanical properties of Fe-rich Si alloys are investigated by combining electronic structure calculations with statistical mechanics means such as the cluster variation method,molecular dynamics simulation,etc,applied to homogeneous and heterogeneous systems.Firstly,we examined the elastic properties based on electronic structure calculations in a homogeneous system and attributed the physical origin of the loss of ductility with increasing Si content to the combined effects of magneto-volume and D03 ordering.As a typical example of a heterogeneity forming a microstructure,we focus on grain boundaries,and segregation behavior of Si atoms is studied through high-precision electronic structure calculations.Two kinds of segregation sites are identified:looser and tighter sites.Depending on the site,different segregation mechanisms are revealed.Finally,the dislocation behavior in the Fe-Si alloy is investigated mainly by molecular dynamics simulations combined with electronic structure calculations.The solid-solution hardening and softening are interpreted in terms of two kinds of energy barriers for kink nucleation and migration on a screw dislocation line.Furthermore,the clue to the peculiar work hardening behavior is discussed based on kinetic Monte Carlo simulations by focusing on the preferential selection of slip planes triggered by kink nucleation.

A Phase-Field Model Coupled with Lattice Kinetics Solver for Modeling Crystal Growth in Furnaces

In this study,we present a new numerical model for crystal growth in a vertical solidification system.This model takes into account the buoyancy induced convective flow and its effect on the crystal growth process.The evolution of the crystal growth interface is simulated using the phase-field method.A semi-implicit lattice kinetics solver based on the Boltzmann equation is employed to model the unsteady incompressible flow.This model is used to investigate the effect of furnace operational conditions on crystal growth interface profiles and growth velocities.For a simple case of macroscopic radial growth,the phase-field model is validated against an analytical solution.The numerical simulations reveal that for a certain set of temperature boundary conditions,the heat transport in the melt near the phase interface is diffusion dominant and advection is suppressed.