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Improved multi-order parameter and multi-component model of polycrystalline solidification

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Journal of Materials Science & Technology 2022年第6期101卷 217-225页

作者： Laishan Yang zhibo dong Lei Wang Nikolas Provatas State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 1Düsseldorf40237Germany Department of Physics and Centre for the Physics of Materials McGill UniversityMontrealH3A 2T8Canada

In this paper, we present an improved multi-order parameter model for multi-component model of polycrystalline solidification. We introduce an interpolation function in the phase field dynamical equation to obtain controllable grain boundary energy at large undercooling. The same interpolation function is also employed in the kinetics coefficient to allow for better control of grain boundary migration. Temperature dependent phase field parameters and noise terms are consistently coupled into the dynamics of a binary system in a manner that allows for quantitative simulations in the thin interface limit. The model is applied to multi-phase solidification in Al-Cu alloy, where a parabolic fitting method is employed to model the free energy of Al-Cu phases and two-phase nucleation is demonstrated in directional solidification.

关键词： Phase field model Multi-phase Multi-component Grain boundary Consistent nucleation

Active-passive radial-additive friction stir repairing of mechanical hole out of dimension tolerance of AZ31 magnesium alloy

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Journal of Magnesium and Alloys 2023年第9期11卷 3186-3199页

作者： Hua Liu Zhenlei Liu Shude Ji Yumei Yue zhibo dong Changlong Chen College of Aerospace Engineering Shenyang Aerospace UniversityShenyang 110136China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radial-additive friction stir repairing(AP-RAFSR) assisted by the truncated cone-shaped filling material was proposed in this study. The mechanical hole out of dimension tolerance of AZ31 magnesium alloy was chosen as the repaired object. The results indicated that the AP-RAFSR process rather than the R-AFSR process avoided the kissing bond in the bottom of the repairing interface under the condition of the tool pin length equal to the height of the standard mechanical hole.The continuously-distributed and large-length super-fine grain bands were eliminated in the stir zone by AP-RAFSR. The maximum tensile and compressive-shear strengths of repaired hole by AP-RAFSR reached 190.6 MPa and 138.9 MPa at 1200 rpm respectively, which were equivalent to 97.7% and 89.6% of those of the standard mechanical hole. This AP-RAFSR process assisted by the truncated cone-shaped filling material provides a new technique to obtain a no-depth-increasing, defect-free and high-strength repaired mechanical hole.

关键词： Active-passive radial-additive friction stir repairing Mechanical hole out of dimension tolerance Numerical simulation Microstructure Mechanical properties

Analysis of interaction between dislocation and interface of aluminum matrix/second phase from electronic behavior

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Journal of Materials Science & Technology 2023年第5期136卷 78-90页

作者： Qianxing Yin Guoqing Chen Xi Shu Binggang Zhang Chun Li zhibo dong Jian Cao Rong An Yongxian Huang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

The inhibitory effect of the second phase on dislocation movement has long been deemed as a great con-tribution to the strengthening of alloys.We investigate the electronic behavior at theα-Al matrix/second phase interface to explore its inhibitory effect on dislocation movement.This work focuses on the dif-ficulty in dislocation movement on the interface ofα-Al/Al_(3)Sc,α-Al/θ’(Al_(2)Cu),andα-Al/T_(1)(Al_(2)CuLi)of aluminum-lithium-scandium alloy based on detailed transmission electron microscopy investigation and electron transport calculation.The more drastic the electron transport between two atoms at the inter-face,the more intense the interaction between them,corresponding to the larger difficulty in breaking and forming bonds between them during the movement process of the extra half plane of dislocation on the interface.The calculated difference in density of valence electrons and differential charge density atα-Al/second phase interface reveals that Al_(3)Sc is characterized by the largest resistance to dislocation movement compared toθ’(Al_(2)Cu)and T_(1)(Al_(2)CuLi).The large differential charge density between the in-terface of(100)Al_(3)Sc/(100)Al demonstrates the strong bonds betweenα-Al and Al_(3)Sc and the large difficulty for the extra half plane of dislocation to form or break bonds during the movement process atα-Al/Al_(3)Sc interface.The dislocation pile-up indicates a discernible hindering effect of theα-Al/Al_(3)Sc interface on dislocation movement.The hindering effect presented byα-Al/Al_(3)Sc interface is favorable for the tensile strength.

关键词： Dislocations Microstructural interface Aluminum alloy Electron transport First-principles calculation

Efficacy and safety of human umbilical cord-derived mesenchymal stem cells in the treatment of refractory immune thrombocytopenia:a prospective,single arm,phase I trial

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Signal Transduction and Targeted Therapy 2024年第5期9卷 2250-2259页

作者： Yunfei Chen Yanmei Xu Ying Chi Ting Sun Yuchen Gao Xueqing Dou zhibo Han Feng Xue Huiyuan Li Wei Liu Xiaofan Liu Huan dong Rongfeng Fu Mankai Ju Xinyue Dai Wentian Wang Yueshen Ma Zhen Song Jundong Gu Wei Gong Renchi Yang Lei Zhang State Key Laboratory of Experimental Hematology National Clinical Research Centre for Blood DiseasesHaihe Laboratory of Cell EcosystemTianjin Key Laboratory of Gene Therapy for Blood DiseasesCAMS Key Laboratory of Gene Therapy for Blood DiseasesInstitute of Hematology&Blood Diseases HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeTianjin 300020China Tianjin Institutes of Health Science Tianjin 301600China National Clinical Research Center for Hematologic Diseases Jiangsu Institute of HematologyThe First Affiliated Hospital of Soochow UniversitySuzhou 215006China National Engineering Research Centre of Cell Products Tianjin Key Laboratory of Engineering Technologies for Cell PharmaceuticalAmCellGene Engineering Co.LtdTianjin 300457China School of Population Medicine and Public Health Chinese Academy of Medical Sciences and Peking Union Medical College100730 BeijingChina

Patients with refractory immune thrombocytopenia(ITP)frequently encounter substantial bleeding risks and demonstrate limited responsiveness to existing therapies.Umbilical cord-derived mesenchymal stem cells(UC-MSCs)present a promising alternative,capitalizing on their low immunogenicity and potent immunomodulatory effects for treating diverse autoimmune disorders.This prospective phase I trial enrolled eighteen eligible patients to explore the safety and efficacy of UC-MSCs in treating refractory ITP.The research design included administering UC-MSCs at escalating doses of 0.5×10^(6)cells/kg,1.0×10^(6)cells/kg,and 2.0×10^(6)cells/kg weekly for four consecutive weeks across three cohorts during the dose-escalation phase,followed by a dose of 2.0×10^(6)cells/kg weekly for the dose-expansion phase.Adverse events,platelet counts,and changes in peripheral blood immunity were monitored and recorded throughout the administration and follow-up period.Ultimately,12(with an addition of three patients in the 2.0×10^(6)cells/kg group due to dose-limiting toxicity)and six patients were enrolled in the dose-escalation and dose-expansion phase,respectively.Thirteen patients(13/18,72.2%)experienced one or more treatment emergent adverse events.Serious adverse events occurred in four patients(4/18,22.2%),including gastrointestinal hemorrhage(2/4),profuse menstruation(1/4),and acute myocardial infarction(1/4).The response rates were 41.7%in the dose-escalation phase(5/12,two received 1.0×10^(6)cells/kg per week,and three received 2.0×10^(6)cells/kg per week)and 50.0%(3/6)in the dose-expansion phase.The overall response rate was 44.4%(8/18)among all enrolled patients.To sum up,UC-MSCs are effective and well tolerated in treating refractory ITP(ClinicalTrials.gov ID:NCT04014166).

关键词： doses immunity treatment

Solute Redistribution with Shear Flow in Molten Pool of Ni-Cr Alloy

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Journal of Materials Science & Technology 2011年第2期27卷 183-188页

作者： zhibo dong Shujuan Wang Rui Ma Yanhong Wei Kuijing Song Guofu Zhai The State Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001China School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001China

Columnar grain growth with shear flow in molten pool of Ni-Cr alloy was simulated with a coupled model of grain growth and solute transport. The results indicate that shear flow alters solute distribution at the vicinity of columnar grains. The solute concentration gradient on the upstream side is greater, while that on the downstream side is smaller, leading to asymmetrical growth of columnar grains. In the interior of a columnar grain, solute concentration increases from the bottom to the dendrite tip, but the rate of increase tends to be reduced. The simulated results are consistent with the experiments.

关键词： Columnar grain growth Fluid flow Solute redistribution Cellular automaton

Residual stress distribution as a function of depth in graphite/copper brazing joints via X-ray diffraction

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Journal of Materials Science & Technology 2019年第11期35卷 2470-2476页

作者： Chun Li Xiaoqing Si Jian Cao Junlei Qi zhibo dong Jicai Feng State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology

The residual stress distributions as a function of depth in three different graphite/copper brazing joints:with no interlayer,with a copper interlayer and with a niobium interlayer are measured via X-ray diffraction by transmission geometry.The residual stress in all the joints is found to be generally compressive and increasing from the surface to the interface.Copper and niobium interlayers are both effective in alleviating the residual stress in the joint and the stress value in the joint with a niobium interlayer appearing to be the lowest.The strength of the joint is demonstrated to be closely related to the residual stress and the fracture position of the joint corresponds well with the highest residual stress.

关键词： Brazing Residual stress XRD Graphite Copper

紫外光诱导氧化钛(110)表面氧空位迁移的成像研究

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Chinese Journal of Chemical Physics 2024年第1期37卷 29-34,I0117页

作者：赵祥云卫东金闲驰江凌马志博杨学明中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023 中国科学院大学北京100049 盛达欧科(北京)分析仪器有限公司北京100044 苏州华杨科学仪器有限公司苏州215300 南方科技大学化学系深圳518055

本文报道了在氧化钛(110)表面上利用扫描隧道显微镜观察到的266 nm紫外激光照射下引发的氧空位迁移.由于紫外光诱导的氧空位迁移,表面上形成了氧空位对甚至氧空位三聚体.氧空位对缺陷有两种稳定的扫描隧道显微镜形态,在扫描过程中可以互... 详细信息

本文报道了在氧化钛(110)表面上利用扫描隧道显微镜观察到的266 nm紫外激光照射下引发的氧空位迁移.由于紫外光诱导的氧空位迁移,表面上形成了氧空位对甚至氧空位三聚体.氧空位对缺陷有两种稳定的扫描隧道显微镜形态,在扫描过程中可以互换.较长的光照时间(68分钟)可以形成以氧空位对为主要点缺陷的氧化钛(110)表面.本文丰富了关于紫外光照射下氧空位行为的理解,为未来涉及266 nm紫外光的金红石型氧化钛(110)还原表面的光催化研究氧空位扩散和氧空位寡聚体形成的现象提供了参考.

关键词：氧化钛扫描隧道显微镜紫外光照氧空位

复杂载荷、极端环境下焊接结构疲劳寿命预测研究综述

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中国机械工程 2024年第5期35卷 829-839页

作者：董志波王程程李承昆李峻臣赵耀邦历吴恺徐爱杰哈尔滨工业大学材料结构精密焊接与连接全国重点实验室哈尔滨150001 上海航天精密机械研究所上海201600

焊接接头易出现缺陷和应力集中,在疲劳载荷作用下将成为疲劳裂纹萌生和扩展的薄弱区域。与均质材料相比,接头各区域微观组织及应力局部化使得焊接结构疲劳问题进一步复杂化。区别于理想实验条件,实际焊接结构服役环境复杂,疲劳寿命预测... 详细信息

焊接接头易出现缺陷和应力集中,在疲劳载荷作用下将成为疲劳裂纹萌生和扩展的薄弱区域。与均质材料相比,接头各区域微观组织及应力局部化使得焊接结构疲劳问题进一步复杂化。区别于理想实验条件,实际焊接结构服役环境复杂,疲劳寿命预测须考虑环境因素与焊接结构耦合特性。为此,对影响焊接结构的内在因素进行总结分析,从复杂载荷和极端服役环境两方面对现有焊接结构寿命预测模型进行综述,结合最新研究进展对改进焊接结构疲劳寿命评估方法提出建议。

关键词：焊接结构影响因素复杂载荷极端环境寿命预测模型

两种丙烯聚合用球形Ziegler-Natta催化剂的性能研究

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现代塑料加工应用 2024年第1期36卷 5-7,22页

作者：郭钦生任合刚刘智博程刘峰董泽中国石油化工股份有限公司茂名分公司广东茂名525021 广东石油化工学院材料科学与工程学院广东茂名525099 山东东宏管业股份有限公司山东济宁273100

采用扫描电子显微镜、激光粒度仪、密度仪和熔体流动速率仪(MFR)等研究了2种丙烯聚合用球形齐格勒-纳塔(Ziegler-Natta)催化剂(记为1#和2#)的性能。结果表明:与2#相比,1#的平均粒径更小,粒径分布更宽,活性更高,对氢气更敏感,且所得聚丙... 详细信息

采用扫描电子显微镜、激光粒度仪、密度仪和熔体流动速率仪(MFR)等研究了2种丙烯聚合用球形齐格勒-纳塔(Ziegler-Natta)催化剂(记为1#和2#)的性能。结果表明:与2#相比,1#的平均粒径更小,粒径分布更宽,活性更高,对氢气更敏感,且所得聚丙烯(PP)堆积密度更高,但PP颗粒粒径较小。不同外给电子体对丙烯聚合的影响不同。采用二环戊基二甲氧基硅烷为外给电子体时,2种催化剂活性均最高,所得PP的MFR均最小。

关键词： Ziegler-Natta催化剂聚合外给电子体聚丙烯