Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第27卷    第10期    总第223期    2017年10月

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文章编号:1004-0609(2017)-10-2029-08
Si对K325铸造高温合金的凝固行为和拉伸性能的影响
肖 旋1,刘庆丰1, 2,王常帅2,周兰章2

(1. 沈阳理工大学 材料科学与工程学院,沈阳 110159; 2. 中国科学院 金属研究所,沈阳 110016)

摘 要: 采用扫描电镜、电子探针和差热分析等方法研究Si含量对铸造高温合金K325凝固行为、组织特征和拉伸性能的影响。结果表明:Si添加粗化枝晶、加重Nb元素偏析且偏析程度随Si含量增加呈增大趋势。不含Si合金的凝固路径为L→L+γ→L+γ+MC→γ+MC,铸态相组成为γ+MC。含Si合金的凝固路径为L→L+γ→L+γ+MC→ L+γ+MC+γ/Laves→γ+MC+γ/Laves,铸态相组成为γ+MC+γ/Laves。此外,随着Si含量的升高,γ/Laves共晶相的尺寸明显增大且量明显增加,形貌由半连续状向连续致密筛网状和花瓣状转变。固溶处理后含Si合金中的γ/Laves共晶消失,相组成为γ+MC+Laves相,Laves相为具有尖锐棱角的块状。随Si含量增加,块状Laves相含量明显增多,Si含量为1.5%(质量分数)时,形成Laves相团簇区。Si对拉伸强度的影响与Si含量密切相关,小于1.0%的Si对合金抗拉强度无明显影响,然而Si含量为1.5%,抗拉强度明显降低。

 

关键字: Si;铸造K325合金;凝固特性;组织特征;拉伸性能

Influence of Si on solidification behaviors and tensile properties of K325 alloy
XIAO Xuan1, LIU Qing-feng1, 2, WANG Chang-shuai2, ZHOU Lan-zhang2

1. School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159, China; 2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

Abstract:The solidification behaviors, microstructure and tensile properties of K325 superalloy were investigated by means of SEM, EPMA, DTA, and so on. The results show that the addition of Si promotes the dendrite coarsening and aggravates the elements segregation of Nb, besides elements segregation increased along with increasing the Si content. The solidification sequence of K325 alloy without Si addition is as follows: L→L+γ→L+γ+MC→γ+MC, and the as-cast microstructure is γ+MC. The solidification sequence of alloys containing silicon is as follows: L→L+γ→L+γ+MC→ L+γ+MC+γ/Laves→γ+MC+γ/Laves, and the as-cast microstructure is γ+MC+γ/Laves. Furthermore, the size and amount of γ/Laves eutectic phase significantly increases with increasing Si content, and the eutectic morphology changes from semi-continuous to continuous dense sieve pattern and petal-like. The γ/Laves eutectic phase disappears after the solution treatment of silicon-containing alloy. The phase composition is γ+MC+Laves phase, and Laves phase is blocky with sharp edges. The amount of Laves phase increases with increasing Si content, and Laves phase comes together into being clusters when Si content is 1.5% (mass fraction). The influence of Si element on tensile strength is closely related to Si content. When Si content is less than 1.0%, Si has no obvious effect on the tensile strength of the alloy, while tensile strength decreases obviously when Si content is 1.5%.

 

Key words: Si; K325; solidification behavior; microstructure; tensile property

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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