Jinfeng Nie, Yuying Wu, Pengting Li, Hui Li and Xiangfa Liu
{"title":"Morphological evolution of TiC from octahedron to cube induced by elemental nickel†","authors":"Jinfeng Nie, Yuying Wu, Pengting Li, Hui Li and Xiangfa Liu","doi":"10.1039/C1CE06205K","DOIUrl":null,"url":null,"abstract":"<p >\r\n TiC particles with various morphologies from octahedron to cube were synthesized and investigated by <annref>Field emission scanning electron microscopy</annref> (<annref>FESEM</annref>) in three-dimensional space. The morphological evolution of TiC grain and its growth mechanism were also discussed. TiC particles <compname>prefer</compname> an octahedral morphology (equilibrium shape) enclosed by eight {111} facets with minimized total surface free energy in Al–Ti–C alloy, while they tend to form a cube enclosed by six {100} facets under the influence of Ni in Al–Ni–Ti–C alloy. Due to the strong interaction between Ni–3d and C–2p orbitals, Ni atoms in the melt selectively absorb on {100} faces of the growing TiC crystal rather than on the polar {111} faces and reduce the specific surface energy of {100}. According to Wuff's theorem, the growth rate of {100} is lowered correspondingly, while the relative growth rate of {111} is accelerated. Thus, the higher growth rate along <111> direction will lead to the shrinkage of {111} faces gradually, while six {100} faces are reserved to form a TiC cube because of their lower growth rates. Furthermore, a similar morphology evolution to TiC crystals can also be found in Fe- and Co-containing melts. It is revealed that the crystal growth of TiC follows the same model under the effect of group VIII elements (Fe, Co and Ni).</p>","PeriodicalId":70,"journal":{"name":"CrystEngComm","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2012-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/C1CE06205K","citationCount":"58","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"CrystEngComm","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2012/ce/c1ce06205k","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 58
Abstract
TiC particles with various morphologies from octahedron to cube were synthesized and investigated by Field emission scanning electron microscopy (FESEM) in three-dimensional space. The morphological evolution of TiC grain and its growth mechanism were also discussed. TiC particles prefer an octahedral morphology (equilibrium shape) enclosed by eight {111} facets with minimized total surface free energy in Al–Ti–C alloy, while they tend to form a cube enclosed by six {100} facets under the influence of Ni in Al–Ni–Ti–C alloy. Due to the strong interaction between Ni–3d and C–2p orbitals, Ni atoms in the melt selectively absorb on {100} faces of the growing TiC crystal rather than on the polar {111} faces and reduce the specific surface energy of {100}. According to Wuff's theorem, the growth rate of {100} is lowered correspondingly, while the relative growth rate of {111} is accelerated. Thus, the higher growth rate along <111> direction will lead to the shrinkage of {111} faces gradually, while six {100} faces are reserved to form a TiC cube because of their lower growth rates. Furthermore, a similar morphology evolution to TiC crystals can also be found in Fe- and Co-containing melts. It is revealed that the crystal growth of TiC follows the same model under the effect of group VIII elements (Fe, Co and Ni).