Cellular/dendritic transition,dendritic growth and microhardness in directionally solidified monophasic Sn-2%Sb alloy  

定向凝固单相Sn-2%Sb合金的胞/枝晶转变、枝晶生长和显微硬度（英文）

作　　者：O.L.ROCHA T.A.COSTA M.DIAS A.GARCIA 

机构地区：[1]Federal hlstitute of Education, Science and technology of Para - IFPA, 66093-020, Belem-Para, Brazil [2]Faculty of mechanical Engineering, Federal University of Para - UFPA, 66075-110, Belem-Para, Brazil [3]Department of Manufacturing and Materials Engineering,University of Campinas-UNICAMP, 13083-860, Campinas-Sao Paulo, Brazil

出　　处：《Transactions of Nonferrous Metals Society of China》2018年第8期1679-1686,共8页中国有色金属学报（英文版）

基　　金：the financial support provided by IFPA, Federal Institute of Education, Science and Technology of Para, FAPESP-Sao Paulo Research Foundation,Brazil (grants 2016/18186-1 and 2017/15158-0);CNPq,The Brazilian Research Council (grants 301600/2015-5; 472745/2013-1 and 308784/2014-6)

摘　　要：Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb（mass fraction） alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate（VL） and the cooling rate（TR）. High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for TR5.0 K/s. Cellular（λc） and primary dendrite arm spacings（λ1） are determined along the length of the directionally-solidified casting. Experimental growth laws relating λc and λ1 to VL and TR are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed.采用单相Sn-2%Sb(质量分数)合金进行水平定向凝固实验,分析凝固热参数对显微组织形貌和长度尺度的影响。在凝固过程中,对沿铸坯长度方向的不同部位进行连续温度测量,用这些温度数据来确定凝固热参数,包括生长速率(V_L)和冷却速率(T_R)。高冷却速率的胞晶和枝晶可以表征铸件不同区域的显微组织,当T_R>5.0 K/s时发生枝晶向胞晶的可逆转变。沿定向凝固铸造的长度方向确定胞晶尺寸(λ_c)和一次枝晶间距(λ_1),提出关于λ_c和λ_1与V_L和T_R的实验生长规律,并与垂直向上定向凝固实验结果进行对比分析,并分析显微组织形貌和长度尺度对显微硬度的影响。

关 键 词：Sn-Sb monophasic alloy directional solidification thermal paIameters inicrostructure reverse cellular/dendritictransition 

分 类 号：TG111.4[金属学及工艺—物理冶金]