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International Journal of Minerals,Metallurgy and materials 2022年第4期29卷 796-806页

作者： Zhangzhi Shi Changheng Li Meng Li Xiangmin Li Luning Wang beijing Advanced Innovation Center for materials Genome Engineering Key Laboratory for Advanced Materials Processing of Ministry of EducationBeijing Laboratory of Metallic Materials and Processing for Modern TransportationSchool of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Many non-toxic alloying elements,such as Fe,Ca,and Sr,have negligible solid solubilities in Zn matrix,leading to formation of coarse second phase particles.They exhibit low strengthening effects but highly detrimental to ductility.So refining second phase is a common pursuit for Zn alloys.The present paper takes Zn-0.3Fe alloy suffered from coarse FeZn_(13) second phase particles as a touchstone to testify microstructure refining effect through solidification with an accelerated speed and multi-pass rolling.FeZn_(13) particles are refined from 24 to 2μm,and Zn grains are refined to 5μm.As a result,the strengthening effect of Fe is enhanced significantly,with yield strength and the ultimate tensile strength of the alloy increased from 132 to 218 MPa and from 159 to 264 MPa,respectively.Furthermore,corrosion non-uniformity and penetration are much alleviated.These results show that microstructure refinement,especially on coarse intermetallic second phases,has a great potential to improve mechanical and degradation properties of biodegradable Zn alloys.

关键词： zinc alloys microstructure mechanical properties corrosion uniformity

Cold compression deformation method for reducing residual stress and uniformizing micro-property in ferrite steel

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Journal of Iron and Steel Research(International) 2022年第3期29卷 503-511页

作者： Bo Ning Hui-bin Wu Gang Niu Xin-pan Yu Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing100083China

To reduce internal residual stress and homogenize micro-property of hot-rolled ferrite steel,the cold compression deformation method with small reduction rate has been performed in the hot-rolled samples,and X-ray diffraction and nanoindentation test have been used to detect the residual stress and micro-property.The samples with deformation rate of 0-5.59%or annealing at 550℃ are analyzed.The results show that,due to the coupling effect of thermal expansion and cold contraction and the volume expansion of microstructural transformation from austenite to ferrite,compressive residual stress was found inside the hot-rolled samples.With the increase in cold compression deformation,the dislocation density increased and the microhardness increased gradually,and there is no obvious rule for the change of mean nano-hardness in micro-zone for the center of samples.However,the uniformity of nano-hardness in the micro-zone increased first and then decreased,and the value of residual stress has obvious corresponding relationship with the uniformity of micro-zone property.The cold compression deformation with appropriate reduction rate can reduce residual stress and improve nano-hardness uniformity of the hot-rolled samples,but more deformation(such as reduction rateε=5.59%)makes residual stress increase and makes uniformity of nano-hardness deteriorate.

关键词： Ferrite Cold compression deformation Residual stress Nano-hardness Uniformity Dislocation density

Effect of prior martensite on bainite transformation and microstructure of high-carbon nano-bainitic steel

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Journal of Iron and Steel Research(International) 2022年第4期29卷 647-654页

作者： Xin-pan Yu Hui-bin Wu Yang Gu Rui Yuan You-you Zhang Yu-hui Feng Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China

Bainite transformation kinetics,microstructure,and mechanical properties were comparably investigated by X-ray diffraction,scanning electron microscopy,electron backscatter diffraction,transmission electron microscopy observation,and tensile and impact tests for two treatments:with and without quenching before isothermal bainite transformation at 300°C.Both the incubation time and growth stage of bainite transformation are accelerated by the introduction of prior martensite,especially the former.In addition,the bainite microstructure around the prior martensite is refined and shows a similar orientation with the martensite due to the strain field caused by the existence of prior martensite.The finer bainite microstructure and prior martensite improve the strength and hardness of the high-carbon nano-bainitic steel.Although the presence of prior martensite and low misorientation relationship between the martensite and the adjacent bainite microstructure are prejudicial to impact toughness,the nanoscale bainite microstructure can inhibit the crack propagation and then improve the impact toughness of the high-carbon nano-bainitic steel.

关键词： Nano-bainitic steel Prior martensite Transformation kinetics Microstructure Mechanical property

Structure design of high-performance Cu-based shape memory alloys

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Rare Metals 2015年第9期34卷 607-624页

作者： Jian-Xin Xie Ji-Li Liu Hai-You Huang State Key laboratory for Advanced Metals and materials University of Science and Technology Beijing Beijing Laboratory of Metallic Materials and Processing for Modern Transportation

The effects of various structure factors on the properties(superelasticity mainly) of Cu-based shape memory alloys(SMAs) were systematically evaluated in this review article through literatures combining with our work. It is concluded that besides the decisive role of grain orientation, the grain boundary(GB) characteristics also play important roles in the superelasticity, which include GB area, GB type, GB morphology and GB direction in descending order of the effect significance. According to the above results, the prior principles of structure design are proposed for high-performance Cu-based SMAs from most to least important:(1) obtaining grain orientation with high phase transformation strain;(2) increasing grain size or reducing GB area;(3) obtaining straight low-energy GBs, especially low-angle GBs;(4) trying to make GB direction parallel to external stress. Consistent with the main or all principles, the bamboo-like-grained and columnar-grained(CG) Cu-based SMAs show excellent comprehensive properties.

关键词： Cu-based shape memory alloy Superelasticity Cu–Al–

Recent progress in the machine learning-assisted rational design of alloys

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International Journal of Minerals,Metallurgy and materials 2022年第4期29卷 635-644页

作者： Huadong Fu Hongtao Zhang Changsheng Wang Wei Yong Jianxin Xie beijing Advanced Innovation Center for materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Key laboratory for Advanced materials processing(MOE) University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China

Alloys designed with the traditional trial and error method have encountered several problems,such as long trial cycles and high costs.The rapid development of big data and artificial intelligence provides a new path for the efficient development of metallic materials,that is,machine learning-assisted design.In this paper,the basic strategy for the machine learning-assisted rational design of alloys was introduced.Research progress in the property-oriented reversal design of alloy composition,the screening design of alloy composition based on models established using element physical and chemical features or microstructure factors,and the optimal design of alloy composition and process parameters based on iterative feedback optimization was reviewed.Results showed the great advantages of machine learning,including high efficiency and low cost.Future development trends for the machine learning-assisted rational design of alloys were also discussed.Interpretable modeling,integrated modeling,high-throughput combination,multi-objective optimization,and innovative platform building were suggested as fields of great interest.

关键词： machine learning data mining rational design alloys

Rapid design of secondary deformation-aging parameters for ultra-low Co content Cu-Ni-Co-Si-X alloy via Bayesian optimization machine learning

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International Journal of Minerals,Metallurgy and materials 2022年第6期29卷 1197-1205页

作者： Hongtao Zhang Huadong Fu Yuheng Shen Jianxin Xie beijing Advanced Innovation Center for materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Key laboratory for Advanced materials processing(MOE) University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China

It is difficult to rapidly design the process parameters of copper alloys by using the traditional trial-and-error method and simultaneously improve the conflicting mechanical and electrical properties.The purpose of this work is to develop a new type of Cu-Ni-Co-Si alloy saving scarce and expensive Co element,in which the Co content is less than half of the lower limit in ASTM standard C70350 alloy,while the properties are as the same level as C70350 alloy.Here we adopted a strategy combining Bayesian optimization machine learning and experimental iteration and quickly designed the secondary deformation-aging parameters(cold rolling deformation 90%,aging temperature 450℃,and aging time 1.25 h)of the new copper alloy with only 32 experiments(27 basic sample data acquisition experiments and 5 iteration experiments),which broke through the barrier of low efficiency and high cost of trial-and-error design of deformation-aging parameters in precipitation strengthened copper alloy.The experimental hardness,tensile strength,and electrical conductivity of the new copper alloy are HV(285±4),(872±3)MPa,and(44.2±0.7)%IACS(international annealed copper standard),reaching the property level of the commercial lead frame C70350 alloy.This work provides a new idea for the rapid design of material process parameters and the simultaneous improvement of mechanical and electrical properties.

关键词： copper alloy process design machine learning Bayesian optimization utility function

Diffusion mechanism of immiscible Fe-Mg system induced by high-density defects at the steel/Mg composite interface

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Journal of materials Science & Technology 2023年第13期144卷 150-160页

作者： Yanlan Sun Xuefeng Liu Wenjing Wang Yaohua Yang Weiliang Zhang beijing Advanced Innovation Center for materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China Key laboratory for Advanced materials processing of Ministry of Education University of Science and Technology BeijingBeijing 100083China

Due to positive mixing heat between Fe and Mg,it is difficult to diffuse for Fe-Mg at the interface of steel/Mg laminated composites,resulting in the inability to achieve high-strength metallurgical bonding.In this paper,20#steel/Mg laminated composites were prepared by large deformation rolling and subse-quent diffusion heat treatment process.The interfacial bonding strength was improved by constructing high-density crystal defects at the interface to promote element diffusion.The mechanisms of interface morphology evolution and element diffusion were analyzed by finite element simulation and theoretical calculation.The results show after diffusion heat treatment,the bond strength of the large deformation rolled interface was increased from 14 to 30 MPa.Fe-Mg transition layer with about 80 nm thickness as well as high-density vacancies,dislocations and grain boundaries were formed in the large deforma-tion rolled interface region.During diffusion heat treatment,Mg elements diffused into grain interior and grain boundary regions of 20#steel under the effect of heat-force coupling,and the thickness of Fe-Mg transition layer increased to 150 nm,forming an Fe-based supersaturated solid solution.The in-terface with high-density defects constituted a non-equilibrium interface.The 20#steel internal energy in the non-equilibrium interface is able to overcome positive mixing heat of immiscible Fe-Mg system and provide the driving force for Mg elements diffusion.Promoting elemental diffusion by constructing high-density defects can be a new concept to achieve metallurgical bonding at the interface of immiscible metal laminated composites.

关键词： Steel/Mg composite interface Immiscible Fe-Mg system Non-equilibrium interface Diffusion mechanism

Effects of Fe content on the microstructure and properties of CuN i10FeM n1 alloy tubes fabricated by HCCM horizontal continuous casting

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International Journal of Minerals,Metallurgy and materials 2016年第4期23卷 449-457页

作者： Yan-bin Jiang Jun Xu Xin-hua Liu Jian-xin Xie Key laboratory for Advanced materials processing of the Ministry of Education University of Science and Technology Beijing Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology Beijing

Heating-cooling combined mold（HCCM） horizontal continuous casting technology developed by our research group was used to produce high axial columnar-grained CuN i10 FeM n1 alloy tubes with different Fe contents. The effects of Fe content（1.08wt%–2.01wt%） on the microstructure, segregation, and flushing corrosion resistance in simulated flowing seawater as well as the mechanical properties of the alloy tubes were investigated. The results show that when the Fe content is increased from 1.08wt% to 2.01wt%, the segregation degree of Ni and Fe elements increases, and the segregation coefficient of Ni and Fe elements falls from 0.92 to 0.70 and from 0.92 to 0.63, respectively. With increasing Fe content, the corrosion rate of the alloy decreases initially and then increases. When the Fe content is 1.83wt%, the corrosion rate approaches the minimum and dense, less-defect corrosion films, which contain rich Ni and Fe elements, form on the surface of the alloy; these films effectively protect the α-matrix and reduce the corrosion rate. When the Fe content is increased from 1.08wt% to 2.01wt%, the tensile strength of the alloy tube increases from 204 MPa to 236 MPa, while the elongation to failure changes slightly about 46%, indicating the excellent workability of the CuNi10FeMn1 alloy tubes.

关键词： copper nickel alloys iron content casting segregation mechanical properties corrosion resistance

Effect of compression direction on the dynamic recrystallization behavior of continuous columnar-grained CuNi10Fe1Mn alloy

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International Journal of Minerals,Metallurgy and materials 2015年第8期22卷 851-859页

作者： Yong-kang Liu Hai-you Huang Jian-xin Xie Key laboratory for Advanced materials processing of the Ministry of Education Institute of Advanced Materials and Technology University of Science and Technology Beijing Beijing Laboratory of Metallic Materials and Processing for Modern Transportation

The dynamic recrystallization（DRX） behavior of continuous columnar-grained（CCG） Cu Ni10Fe1 Mn alloy was investigated by hot compression along the solidification direction（SD） and perpendicular to the solidification direction（PD）. Specimens were compressed to a true strain of 0.8 at temperatures ranging from 25°C to 900°C and strain rates ranging from 0.01 to 10 s-1. The results indicate that DRX nucleation at grain boundaries（GBs） and DRX nucleation at slip bands（SBs） are the two main nucleation modes. For SD specimens, C-shaped bending and zig-zagging of the GBs occurred during hot compression, which made DRX nucleation at the GBs easier than that at the SBs. When ln Z ≤ 37.4（Z is the Zener–Hollomon parameter）, DRX can occur in SD specimens with a critical temperature for the DRX onset of;50°C and a thermal activated energy（Q） of 313.5 k J·mol-1. In contrast, in PD specimens, the GBs remained straight, and DRX nucleation occurred preferentially at the SBs. For PD specimens, the critical temperature is about 700°C, Q is 351.7 k J·mol-1, and the occurrence condition of DRX is ln Z ≤ 40.1. The zig-zagging of GB morphology can significantly reduce the nucleation energy at the GBs; as a result, DRX nucleation occurs more easily in SD specimens than in PD specimens.

关键词： copper–nickel alloys columnar grains compressive d

The precipitation behaviours and strengthening mechanism of a Cu-0.4 wt% Sc alloy

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Journal of materials Science & Technology 2022年第3期98卷 1-13页

作者： Zifan Hao Guoliang Xie Xinhua Liu Qing Tan Rui Wang State Key laboratory for Advanced Metals and materials University of Science and Technology BeijingBeijing100083China Key laboratory for Advanced materials processing of Ministry of Education Institute of Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing100083China

The precipitation behaviours during the aging process and the corresponding strengthening mechanism of a Cu-0.4 wt%Sc alloy were systematically investigated in this study.The phase transformation sequence of the precipitation in the aging process of the Cu-0.4 wt%Sc alloy was found to be:supersaturated solid solution→Sc-enriched atomic clusters→metastable phase→Cu4Sc phase.The tetragonal structured lamellar Cu4Sc precipitates,with a habit plane parallel to the{111}plane of the Cu matrix and orientation relationships of(022)_(α)//(211)_(Cu4Sc)and[011]_(α)//[113]_(Cu4Sc),are found homogeneously distributed in the matrix.A combined process of cryogenic rolling(CR)and aging was designed for optimization of the mechanical and electrical properties.Excellent integration of yield strength(696 MPa)and electrical conductivity(62.8%IACS)of this alloy was achieved by cryogenic rolling and subsequent aging process at 400℃for 4 h.The significant precipitation strengthening effect of this alloy is attributed to the Cu4Sc precipitates with an extremely small size of only 1.5–3 nm.The leading strengthening mechanism is considered as the superposition of both coherent strengthening and Orowan strengthening effects.

关键词： Cu-Sc alloy Precipitation Aging process Strengthening mechanism