Sun Kui, Zhang Jian-fei, Guo Ming-yang, Li Zhen-liang, Cen Yao-dong, ZHANG Hai-xia
{"title":"Microstructure and Mechanical Properties of Nickel-Microalloyed Cr-19Si Alloys","authors":"Sun Kui, Zhang Jian-fei, Guo Ming-yang, Li Zhen-liang, Cen Yao-dong, ZHANG Hai-xia","doi":"10.1016/j.jallcom.2025.179136","DOIUrl":null,"url":null,"abstract":"The effects of trace Ni addition on the microstructure and mechanical properties of Cr-19Si hypereutectic alloy were studied. The existence of the Ni element added to the as-cast alloy and the refinement mechanism of primary Cr<sub>3</sub>Si dendrites were analyzed and studied. The results show that after the addition of Ni element, a small amount of Ni is dissolved into the two-phase structure, and the intermetallic compound Cr<sub>3</sub>NiSi is formed at the grain boundary, and a new Ni-rich phase Cr<sub>8</sub>NiSi is formed in the crystal. It can also effectively refine the Cr<sub>3</sub>Si dendrites and expand the proportion of Cr<sub>ss</sub> in the solidified structure. The room temperature properties of the alloy also change significantly with the addition of Ni. When 1<!-- --> <!-- -->wt.% Ni is added, the room temperature performance of the alloy is improved the most; the room temperature compression performance is improved by about three times, the microhardness is increased by 3.8%, and the room temperature fracture toughness is increased by 23.8%. It is mainly caused by the strengthening of fine grain, solid solution, and dispersion, which are caused by the addition of Ni. Based on the BCT dendrite growth model and the M-T fast eutectic solidification model, the competitive growth of the Cr<sub>3</sub>Si dendrite and eutectic microstructure during the solidification of the Cr-19Si alloy was calculated. Combined with the effect of Ni addition on the solidification morphology, the effects of Ni addition on dendrite growth and melt undercooling were analyzed. The results show that when the undercooling is lower than 31.4356<!-- --> <!-- -->K, the growth rate of eutectic structures is higher than that of Cr<sub>3</sub>Si dendrites. When the undercooling is higher than 31.4356<!-- --> <!-- -->K, the growth rate of Cr<sub>3</sub>Si dendrite begins to increase rapidly and exceeds the growth rate of eutectic structures. The addition of Ni can decrease the tip radius of the Cr<sub>3</sub>Si dendrites and increase the undercooling of the Cr<sub>3</sub>Si dendrites during solidification.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"12 1","pages":""},"PeriodicalIF":6.3000,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Alloys and Compounds","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1016/j.jallcom.2025.179136","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The effects of trace Ni addition on the microstructure and mechanical properties of Cr-19Si hypereutectic alloy were studied. The existence of the Ni element added to the as-cast alloy and the refinement mechanism of primary Cr3Si dendrites were analyzed and studied. The results show that after the addition of Ni element, a small amount of Ni is dissolved into the two-phase structure, and the intermetallic compound Cr3NiSi is formed at the grain boundary, and a new Ni-rich phase Cr8NiSi is formed in the crystal. It can also effectively refine the Cr3Si dendrites and expand the proportion of Crss in the solidified structure. The room temperature properties of the alloy also change significantly with the addition of Ni. When 1 wt.% Ni is added, the room temperature performance of the alloy is improved the most; the room temperature compression performance is improved by about three times, the microhardness is increased by 3.8%, and the room temperature fracture toughness is increased by 23.8%. It is mainly caused by the strengthening of fine grain, solid solution, and dispersion, which are caused by the addition of Ni. Based on the BCT dendrite growth model and the M-T fast eutectic solidification model, the competitive growth of the Cr3Si dendrite and eutectic microstructure during the solidification of the Cr-19Si alloy was calculated. Combined with the effect of Ni addition on the solidification morphology, the effects of Ni addition on dendrite growth and melt undercooling were analyzed. The results show that when the undercooling is lower than 31.4356 K, the growth rate of eutectic structures is higher than that of Cr3Si dendrites. When the undercooling is higher than 31.4356 K, the growth rate of Cr3Si dendrite begins to increase rapidly and exceeds the growth rate of eutectic structures. The addition of Ni can decrease the tip radius of the Cr3Si dendrites and increase the undercooling of the Cr3Si dendrites during solidification.
期刊介绍：
The Journal of Alloys and Compounds is intended to serve as an international medium for the publication of work on solid materials comprising compounds as well as alloys. Its great strength lies in the diversity of discipline which it encompasses, drawing together results from materials science, solid-state chemistry and physics.
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