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Assessment of solidification characteristics of carbon-inoculated Mg-3%Al melt by thermal analysis

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Transactions of Nonferrous Metals Society of China 2018年第4期28卷 812-818页

作者： Jun DU Yu-tong SHI Wen-fang LI School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China

The Mg-3%Al melt was inoculated by carbon with different holding *** effect of holding time on grain refining efficiency was *** solidification characteristics of the carbon-inoculated Mg-3%Al melt with different holding time were assessed by computer-aided cooling curve *** results showed that Mg-3%Al alloy could be effectively refined by carbon *** fading phenomenon occurred with increasing the holding time to 60 *** inoculation could significantly influence the shape of cooling curves of Mg-3%Al *** nucleation starting and minimum temperatures *** recalescence undercooling and duration decreased to almost zero after carbon *** grain refining efficiency of carbon inoculation could be assessed by the shape of the cooling curve and solidification characteristic parameters including nucleation starting and minimum temperatures,recalescence undercooling and duration.

关键词： Mg-Al alloy grain refinement carbon inoculation solidification characteristics computer-aided cooling curve analysis

Effect of cerium on microstructure,eutectic carbides and Laves phase in electroslag remelted 15Cr-22Ni-1Nb austenitic heat-resistant steel

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Journal of Iron and Steel Research International 2023年第2期30卷 338-349页

作者： Xin Zhu Cheng-bin Shi Shi-jun Wang Peng Lan Jing Li State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing(USTB)Beijing100083China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing100083China

The dendrites,eutectic carbides,Laves phase and microsegregation of alloying element in electroslag remelted 15Cr-22Ni-1Nb austenitic heat-resistant steel with varying cerium contents were *** liquidus and solidus temperatures of the steel were determined to reveal the effect of cerium on solidification temperature interval and local solidification time of the *** secondary dendrite arm spacing decreases from 57.10 to 40.18μm with increasing the cerium content from 0 to 0.0630 wt.%.The eutectic NbC and Laves phase in as-cast ingots exhibit blocky and honeycomb morphology,*** area fractions and sizes of eutectic NbC and Laves phase in as-cast ingots decrease with the increase in cerium *** atomic percentage of Laves phase-forming element(Ni,Nb,Cr,Mo and Si)decreases with the increase in cerium content of the *** microsegregation of Mo,Ni,Si,Cr and Nb decreases with increasing the cerium content,which is favorable to reducing both the amount and sizes of eutectic NbC and Laves phase in as-cast *** solidification temperature interval and local solidification time of the steel decrease as the cerium content is increased from 0 to 0.0630 wt.%,which inhibits the growth of dendrites,eutectic NbC and Laves phase.

关键词： Heat-resistant steel Rare earth cerium Eutectic NbC Laves phase Microsegregation solidification characteristics

Effect of Melt Superheating Treatment on Directional solidification Interface Morphology of Multi-component Alloy

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Journal of Materials Science & Technology 2011年第7期27卷 668-672页

作者： Changshuai Wang Jun Zhang Lin Liu Hengzhi Fu State Key Laboratory of solidification Processing Northwestern Polytechnical University Xi an 710072 China

The influence of melt superheating treatment on the solid/liquid （S/L） interface morphology of directionally solidified Ni-based superalloy DZ125 is investigated to elucidate the relationship between melt characteristic and S/L interface stability. The results indicate that the interface morphology is not only related to the withdrawal velocity （R） but also to the melt superheating temperature （Ts） when the thermal gradient of solidification interface remains constant for different Ts with appropriate superheating treatment regulation. The interface morphology changes from cell to plane at R of 1.1 μm/s when Ts increases from 1500°C to 1650°C, and maintains plane with further elevated Ts of 1750°C. However, the interface morphology changes from coarse dendrite to cell and then to cellular dendrite at R of 2.25 μm/s when Ts increases from 1500°C to 1650°C and then to 1750°C. It is proved that the solidification onset temperature and the solidification interval undergo the nonlinear variation when Ts increases from 1500°C to 1680°C, and the turning point is 1650°C at which the solidification onset temperature and the solidification interval are all minimum. This indicates that the melt superheating treatment enhances the solidification interface stability and has important effect on the solidification characteristics.

关键词： Melt superheating treatment Directional solidification interface morphology solidification characteristics Multi-component alloy

Preparation of sulfoaluminate cementitious material using harmful titanium gypsum:material properties and heavy metal immobilization characteristics

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Waste Disposal and Sustainable Energy 2020年第2期2卷 127-137页

作者： Jingwei Li Wenlong Wang Dong Xu Xujiang Wang Yanpeng Mao Shandong Engineering Laboratory for Solid Waste Green Materials National Engineering Laboratory for Reducing Emissions From Coal CombustionEngineering Research Center of Environmental Thermal Technology of Ministry of EducationShandong Key Laboratory of Energy Carbon Reduction and Resource UtilizationSchool of Energy and Power EngineeringShandong UniversityJinan 250061ShandongChina School of Civil Engineering Shandong Jianzhu UniversityJinan 250101China

The production of titanium dioxide(a necessary industrial color additive)can generate massive amount of titanium gypsum,a hard-to-treat solid *** metallic impurities,heavy metals and reddish color in titanium gypsum make it difficult to be used in building materials like other by-product *** a result,most of titanium gypsum in China is just stored and has caused serious environmental *** this study,titanium gypsum,which contained high contents of impurities and heavy metals,was synergistically used with other three solid wastes to prepare sulfoaluminate cementitious material(SACM)for the first *** mass proportion of titanium gypsum in the raw materials exceeded 25%.The chemical,mechanical and heavy metal leaching characteristics of this solid waste-based SACM were tested via XRD,XRF,ICP-OES,*** main components and metallic impurities of titanium gypsum could be transformed to the components of the main mineral of SACM,ye’*** compressive strength of the prepared SACM reached 38.2,59.7 and 95.8 MPa at 1-day,3-day,and 28-day hydration,respectively,indicating the features of rapidly hardening and high ***,the solid waste-based SACM could effectively solidify the heavy metals contained in titanium gypsum and other raw material during thje hydration *** retention ratio of total Cr reached 97.5%,and other heavy metals were almost not detected in the leachate of *** study provided a feasible approach to utilize titanium gypsum to produce high-performance,green building material,and might promote the massive utilization of this solid waste.

关键词： Titanium gypsum Solid waste Sulfoaluminate cementitious material Synergistic utilization Heavy metals solidification characteristics

Vertical section phase diagrams of La−Fe−B ternary system

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Transactions of Nonferrous Metals Society of China 2021年第6期31卷 1748-1757页

作者： Qi WEI Zhao LU Qing-rong YAO Jian-qiu DENG Jiang WANG Huai-ying ZHOU Guang-hui RAO Guangxi Key Laboratory of Information Materials School of Materials Science and EngineeringGuilin University of Electronic TechnologyGuilin 541004China School of Physical Science and Technology Guangxi UniversityNanning 530004China Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials Nanning 530004China

The vertical sections of the La−Fe−B system were investigated using electron probe microanalysis and differential thermal *** on the microstructures and phase compositions of the as-cast and equilibrium alloys,together with their heat flow−temperature curves,phase diagrams for three vertical sections were drawn:La_(x)Fe_(82)B_(y)(x+y=18),La_(x)Fe_(70)B_(y)(x+y=30)and La_(x)Fe_(53)B_(y)(x+y=47),where x and y represent mass fraction of La and B,respectively,%.Additionally,according to the phase diagrams,the compound La2Fe14B was identified as a stable phase at high *** was found to be stable between 926.2 and 792.6℃;at low temperatures,however,it decomposed into α-La,α-Fe and LaFe_(4)B_(4),according to the reaction La_(2)Fe_(14)B→α-Fe+α-La+LaFe_(4)B_(4).

关键词： solidification characteristics vertical section phase diagram equilibrium alloy high temperature stable compound