K4208高温合金中析出相的表征

K4208高温合金中W、Mo含量比较高,通常会形成碳化物和金属间相。为了对K4208高温合金中析出相做定性定量分析,通过实验选择了合适的电解条件:电解液为10g/L氯化锂-40g/L磺基水杨酸-5%(V/V)甘油甲醇溶液,电流密度为0.04~0.06A/cm²,电解温度为0~-5℃。采用电解萃取方法将析出相从合金基体中分离,研究了析出相的分离方法,将碳化物溶解,得到了单独新相。通过X射线衍射(XRD)测定了析出相的点阵常数,用X射线小角散射法测定析出相的粒度分布。采用扫描电镜(SEM)研究了析出相的形貌和元素组成,用电感耦合等离子体原子发射光谱法(ICP-AES)测定了析出相中各元素含量及析出相总量。结果表明:电解条件对析出相的萃取量影响明显,K4208高温合金中有新相、γ′、M₆C和M₁₂C这4种析出相。新相的稳定性比较高,不溶于6%(V/V)H₂SO₄-20%(V/V)H₂O₂溶液和20%(V/V)HCl乙醇溶液,在50%(V/V)H₂SO₄中部分溶解。M₆C和M₁₂C相呈块状,粒径相对较小,混合相的平均粒径为170.7nm;新相呈片状,颗粒粗大,平均粒径为216.6nm。

Characterization of the precipitated phases in K4208 high temperature alloy

The contents of W and Mo in K4208 high temperature alloy are relatively high. The carbide and intermetallic phases are usually formed. In order to qualitatively and quantitatively analyze the precipitated phases in K4208 high temperature alloy, the proper electrolytic conditions were selected in experiments: the electrolyte was 10g/L lithium chloride-40g/L sulfosalicylic acid-5% (V/V) glycerol methanol solution; the current density was 0.04-0.06A/cm²; the electrolysis temperature was between 0℃ and -5℃. The precipitated phases were separated from alloy matrix by electrolytic extraction method. The separation methods of precipitated phases were studied. The carbides were dissolved and the single new phase was obtained. The lattice constant of precipitated phases was measured by X-ray diffraction (XRD). The size distribution of precipitated phases was measured by X-ray small angle scattering method. The morphology and element composition were analyzed by scanning electron microscope (SEM). The elemental content and total content of precipitated phases were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that the extraction amount of precipitated phases was significantly affected by the electrolytic conditions. The K4208 high temperature alloy contained four precipitated phases, i.e., new phase, γ′ phase, M₆C phase and M₁₂C phase. The stability of new phase was high and it was insoluble in 6% (V/V) H₂SO₄-20% (V/V) H₂O₂ solution and 20% (V/V) HCl ethanol solution, and partially dissolved in 50% (V/V) H₂SO₄. M₆C phase and M₁₂C phase were blocky with relatively small particle size. The average particle size of mixed phase was 170.7nm. The new phase was lamellar with large particles, and the average particle size was 216.6nm.