{"title":"Disorder trapping and recrystallization-induced grain refinement in undercooled Ni3Ga melts","authors":"","doi":"10.1016/j.scriptamat.2024.116275","DOIUrl":null,"url":null,"abstract":"<div><p>The mechanism of grain refinement in undercooled Ni<sub>3</sub>Ga melts was investigated. An in situ diagnosis of the dendrite growth velocity using a high-speed camera indicates direct crystallization of the Ni<sub>3</sub>Ga compound and disorder trapping at a critical undercooling of 68 K and 120 K, respectively. An EBSD analysis shows a grain-refined microstructure for samples with undercoolings of 120 K and 148 K in contrast to a coarse-grained microstructure for the sample with an undercooling of 89 K. HRTEM investigation shows a mixture of a disordered solid solution and the ordered Ni<sub>3</sub>Ga compound in the atomic-scale microstructure of each sample in agreement with X-ray and neutron diffraction analyses. Microhardness tests show that disorder trapping reduces the mechanical strength of the samples in spite of grain refinement. It is concluded that disorder trapping promotes plastic deformation of the Ni<sub>3</sub>Ga compound and that grain refinement is induced by recrystallization after rapid solidification processing.</p></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":null,"pages":null},"PeriodicalIF":5.3000,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Scripta Materialia","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1359646224003105","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The mechanism of grain refinement in undercooled Ni3Ga melts was investigated. An in situ diagnosis of the dendrite growth velocity using a high-speed camera indicates direct crystallization of the Ni3Ga compound and disorder trapping at a critical undercooling of 68 K and 120 K, respectively. An EBSD analysis shows a grain-refined microstructure for samples with undercoolings of 120 K and 148 K in contrast to a coarse-grained microstructure for the sample with an undercooling of 89 K. HRTEM investigation shows a mixture of a disordered solid solution and the ordered Ni3Ga compound in the atomic-scale microstructure of each sample in agreement with X-ray and neutron diffraction analyses. Microhardness tests show that disorder trapping reduces the mechanical strength of the samples in spite of grain refinement. It is concluded that disorder trapping promotes plastic deformation of the Ni3Ga compound and that grain refinement is induced by recrystallization after rapid solidification processing.
研究了欠冷 Ni3Ga 熔体中晶粒细化的机理。使用高速照相机对树枝状晶生长速度进行的现场诊断表明,在临界过冷度分别为 68 K 和 120 K 时,Ni3Ga 化合物会直接结晶并发生无序捕集。EBSD 分析表明,过冷度分别为 120 K 和 148 K 的样品具有晶粒细化的微观结构,而过冷度为 89 K 的样品则具有粗粒微观结构。显微硬度测试表明,尽管晶粒细化,但无序捕集降低了样品的机械强度。结论是无序捕集促进了 Ni3Ga 化合物的塑性变形,而晶粒细化是由快速凝固加工后的再结晶引起的。
期刊介绍:
Scripta Materialia is a LETTERS journal of Acta Materialia, providing a forum for the rapid publication of short communications on the relationship between the structure and the properties of inorganic materials. The emphasis is on originality rather than incremental research. Short reports on the development of materials with novel or substantially improved properties are also welcomed. Emphasis is on either the functional or mechanical behavior of metals, ceramics and semiconductors at all length scales.