不同Ru含量镍基高温合金微观组织和热腐蚀行为研究
发布时间：2018-09-01 12:05
【摘要】：钌(Ru)作为镍基高温合金发展过程中的关键元素,其在合金中的作用备受关注。大多数研究主要针对含Ru的单晶高温合金,但对于含Ru的多晶镍基高温合金的研究罕见报道。本文将系统研究Ru对多晶镍基高温合金的组织、合金元素偏析、凝固过程、密度、硬度、显微疏松和热腐蚀性能影响。采用真空熔模铸造制备实验合金和涂盐腐蚀方法研究合金热腐蚀性能。利用光学显微镜、电子扫描电镜、电子探针、差热分析系统等设备进行检测和分析合金的相组成分布、偏析行为、凝固过程、腐蚀机理。通过研究发现合金铸态组织主要由γ相、γ'相、γ/γ'共晶和MC型碳化物组成。随着Ru含量增加,合金的铸态组织枝晶干和枝晶间的γ'体积分数和尺寸均减小,γ'正方度和共晶的面积分数逐渐增加。合金经过热处理后,初生的γ'和共晶组织完全溶解,合金的相组成为γ相、γ'相和MC型碳化物。热处理后合金中的γ'体积分数及尺寸随着Ru的添加而减小。随着Ru含量的增加,合金的密度增大,硬度提高,合金中的疏松减少。Ru的添加有益于抑制合金铸造过程中疏松形成。Ru的添加改变了Cr、Mo的偏析特性,即从负偏析元素转变为正偏析元素,同时促进W的偏析程度。随着Ru含量的增加,正偏析元素Ta、Ti的偏析程度增加但Al的偏析程度减小,Ru略偏析于枝晶间。Ru的加入降低了γ'初始溶解温度和合金的固相线温度,但对合金的液相线温度没有影响。随着Ru的加入,合金终凝温度(tf)和γ'析出温度(tpγ')降低,凝固温度区间(?t′)变宽。在900℃涂覆75%Na2SO4+25%Na Cl混合盐的同等条件下,0Ru合金的抗热腐蚀性能最差,随着Ru含量的增加,合金抗腐蚀性能增强。4种不同Ru含量合金的热腐蚀进程按照硫化-氧化机理进行。高Cr无Re多晶镍基高温合金中加入Ru元素有益于提高合金的抗热腐蚀能力。
[Abstract]:As a key element in the development of nickel-based superalloys, ruthenium (Ru) has attracted much attention. Most of the studies are focused on single crystal superalloys containing Ru, but few studies on polycrystalline nickel based superalloys containing Ru are reported. In this paper, the effects of Ru on the microstructure, segregation, solidification, density, hardness, microporosity and hot corrosion of polycrystalline nickel based superalloys are systematically studied. The hot corrosion properties of the alloy were studied by vacuum investment casting and salt corrosion. The phase composition distribution, segregation behavior, solidification process and corrosion mechanism of the alloy were detected and analyzed by optical microscope, electron scanning electron microscope, electron probe and differential thermal analysis system. It is found that the as-cast microstructure of the alloy is mainly composed of 纬 phase, 纬 'phase, 纬 / 纬' eutectic and MC type carbides. With the increase of Ru content, the volume fraction and size of 纬 'between dendrite and dry dendrite in as-cast microstructure decreased, and the 纬' square degree and eutectic area fraction increased gradually. After heat treatment, the primary 纬 'and eutectic structure were completely dissolved, and the phase composition of the alloy was 纬 phase, 纬' phase and MC type carbide. After heat treatment, the volume fraction and size of 纬'in the alloy decreased with the addition of Ru. With the increase of Ru content, the density of the alloy increases, the hardness increases, and the porosity decreases. The addition of Ru is beneficial to restrain the formation of porosity. Ru in the casting process of the alloy changes the segregation characteristics of Cr,Mo. That is, from negative segregation element to positive segregation element, and to promote the segregation degree of W at the same time. With the increase of Ru content, the degree of segregation of positive segregation element Ta,Ti increases, but the degree of segregation of Al decreases. The addition of Ru to the intergranular phase decreases the initial dissolution temperature of 纬 'and the solid-state line temperature of the alloy. However, there is no effect on the liquid line temperature of the alloy. With the addition of Ru, the final setting temperature (tf) and 纬 'precipitation temperature (tp 纬') of the alloy decreased, and the solidification temperature range (t') became wider. The thermal corrosion resistance of 0 Ru alloy was the worst under the same condition of 75%Na2SO4 25%Na Cl mixed salt coating at 900 鈩，
本文编号：2217149
[Abstract]:As a key element in the development of nickel-based superalloys, ruthenium (Ru) has attracted much attention. Most of the studies are focused on single crystal superalloys containing Ru, but few studies on polycrystalline nickel based superalloys containing Ru are reported. In this paper, the effects of Ru on the microstructure, segregation, solidification, density, hardness, microporosity and hot corrosion of polycrystalline nickel based superalloys are systematically studied. The hot corrosion properties of the alloy were studied by vacuum investment casting and salt corrosion. The phase composition distribution, segregation behavior, solidification process and corrosion mechanism of the alloy were detected and analyzed by optical microscope, electron scanning electron microscope, electron probe and differential thermal analysis system. It is found that the as-cast microstructure of the alloy is mainly composed of 纬 phase, 纬 'phase, 纬 / 纬' eutectic and MC type carbides. With the increase of Ru content, the volume fraction and size of 纬 'between dendrite and dry dendrite in as-cast microstructure decreased, and the 纬' square degree and eutectic area fraction increased gradually. After heat treatment, the primary 纬 'and eutectic structure were completely dissolved, and the phase composition of the alloy was 纬 phase, 纬' phase and MC type carbide. After heat treatment, the volume fraction and size of 纬'in the alloy decreased with the addition of Ru. With the increase of Ru content, the density of the alloy increases, the hardness increases, and the porosity decreases. The addition of Ru is beneficial to restrain the formation of porosity. Ru in the casting process of the alloy changes the segregation characteristics of Cr,Mo. That is, from negative segregation element to positive segregation element, and to promote the segregation degree of W at the same time. With the increase of Ru content, the degree of segregation of positive segregation element Ta,Ti increases, but the degree of segregation of Al decreases. The addition of Ru to the intergranular phase decreases the initial dissolution temperature of 纬 'and the solid-state line temperature of the alloy. However, there is no effect on the liquid line temperature of the alloy. With the addition of Ru, the final setting temperature (tf) and 纬 'precipitation temperature (tp 纬') of the alloy decreased, and the solidification temperature range (t') became wider. The thermal corrosion resistance of 0 Ru alloy was the worst under the same condition of 75%Na2SO4 25%Na Cl mixed salt coating at 900 鈩，
本文编号：2217149
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