Thermodynamics of the oxygen solutions in zirconium-containing iron-nickel melts

Thermodynamic analysis of the oxygen solutions in zirconium-containing iron-nickel melts is carried out. The equilibrium deoxidation constants of the melts by zirconium, the activity coefficients at infinite dilution, and the interaction parameters in melts of various compositions are determined. The dependences of the oxygen solubility in the melts on the nickel or zirconium content are calculated. Zirconium is shown to possess a very high deoxidizing capacity in iron-nickel alloys. The zirconium contents at the minima in oxygen solubility curves and the corresponding minimum oxygen concentrations are determined. As the nickel content in a melt increases to ∼45%, the deoxidizing capacity of zirconium decreases and, then, increases. The deoxidizing capacity of zirconium in pure nickel is noticeably higher than that in pure iron.     

Thermodynamics of oxygen solutions in Fe-Ni-V melts

The oxygen solutions in Fe-Ni melts with up to 5% V are analyzed thermodynamically. The results of the works in which the fields of the vanadium-deoxidized oxide phases in iron and nickel were determined are generalized. The thermodynamic model developed for the calculation of the deoxidation of iron-nickel alloys with vanadium is shown to be adequate. The deoxidizing capacity of vanadium decreases insignificantly as the nickel content in the melt increases to 20% and increases substantially as the nickel content increases further. The oxygen solubility curves pass through a minimum, whose position changes from 2.3192% V for pure iron to 0.7669% V for pure nickel. We determined the equilibrium point [V]* between the (Fe, Ni)V₂O₄ and V₂O₃ oxide phases for alloys of six compositions at 1873 K. In nickel, [V]* is almost 200 times lower than in iron. The deoxidation of the Fe-40% Ni melt with vanadium is studied experimentally, and the experimental results agree satisfactorily with the calculated data.     

Thermodynamics of the oxygen solutions in niobium-containing Fe-Ni melts

A thermodynamic analysis is performed for the oxygen solutions in niobium-containing Fe-Ni melts. The deoxidizing capacity of niobium in iron??nickel melts is shown to be low. It decreases slightly as the nickel content in a melt increases to 40% and then increases insignificantly as the nickel content increases to 60%; a further increase in the nickel content leads to a marked increase in the deoxidizing capacity. The solubility curves of oxygen in iron??nickel melts passes through a minimum, whose position shifts toward higher niobium concentrations with increasing nickel content. Subsequent niobium additions increase the oxygen concentration in the melt. The equilibrium constants of the reactions of niobium deoxidizing of iron??nickel melts, the activity coefficients, and the interaction parameters characterizing Fe-Ni-Nb-O melts are determined.     

Thermodynamics of the oxygen solutions in aluminum-containing Fe-Co melts

Thermodynamic analysis of aluminum-containing Fe-Co melts is performed. The equilibrium constants of the deoxidation of iron-cobalt melts with aluminum, the activity coefficients during infinite dilution, and the interaction parameters in melts with various compositions are determined. The oxygen solubility in the melts under study is studied as a function of the cobalt and aluminum contents. Aluminum is characterized by a very high affinity to oxygen in iron-cobalt melts. The deoxidizing capacity of aluminum substantially increases with the cobalt content in the melt. The curves of the oxygen solubility in aluminum-containing iron-cobalt melts have a minimum, whose position shifts to lower aluminum contents as the cobalt content in the melt increases. Further aluminum additions increase the oxygen concentration in the melt: the higher the cobalt content in the melt, the sharper the increase in the oxygen concentration after the minimum when aluminum is added to the melt. The aluminum contents at the minimum points in the oxygen solubility curves are determined, and the corresponding minimum oxygen concentrations are found.     

Oxygen solubility in silicon-containing Fe-Co melts

Thermodynamic analysis of the oxygen solutions in silicon-containing Fe-Co melts is performed. The equilibrium constant of silicon deoxidation of iron-cobalt melts, the activity coefficients for infinite dilution, and the interaction parameters for melts differing in composition are determined. The dependences of the oxygen solubility in the melts under study are calculated for different cobalt and silicon contents. The deoxidizing capacity of silicon increases substantially as the cobalt content in a melt increases. The curves of oxygen solubility in Fe-Co melts have a minimum; the minimum oxygen solubility shifts to a low silicon content as the cobalt content in the melts increases. The silicon contents for the minima in the curves of oxygen solubility and the minimum oxygen concentrations corresponding to the silicon contents are determined.     

Thermodynamics of titanium-based melts: II. Oxygen in liquid titanium

A method for the conversion of the thermodynamic characteristics of iron-based melts into those of titanium-based melts is used to calculate the change in the Gibbs free energy when oxygen dissolves in liquid titanium and when titanium is deoxidized by deoxidizing elements. It is established that beryllium is the most rational deoxidizer for structural, high-temperature, and functional titanium alloys and calcium is the most rational deoxidizer for foundry alloys. Free oxygen or volatile monoxides from liquid titanium cannot pass to a gaseous medium in vacuum, since it needs an unattainably low residual pressure.     

Thermodynamics of the oxygen solutions in Fe-Ni-Ti melts

The oxygen solutions in Fe-Ni melts containing up to 3% titanium are analyzed thermodynamically. The results of the works that determined the fields of the oxide phases in iron and nickel deoxidized by titanium are generalized. The proposed calculation model is shown to adequately describe the titanium deoxidation of iron-nickel alloys. The deoxidizing capacity of titanium decreases as the nickel content in the melt increases to 40% and, then, increases sharply as the nickel content increases further. The oxygen solubility curves pass through a minimum, whose position changes from 0.5644% Ti for pure iron to 0.6332% Ti for pure nickel. The points of equilibrium between the TiO₂, Ti₃O₅, and Ti₂O₃ oxide phases are determined for six alloy compositions at 1873 K. The titanium deoxidation of Fe-40% Ni melts is experimentally studied, and the calculated and experimental results are in good agreement.     

Thermodynamics of the oxygen solutions in manganese-containing Fe-Co melts

Thermodynamic analysis of the oxygen solutions in manganese-containing Fe-Co melts has been performed. The equilibrium constants of deoxidation reaction of iron-cobalt melts with manganese, the activity coefficients during infinity dilution, and the interaction parameters in various melts are found. During the deoxidation of manganese-containing Fe-Co melts, the oxide phase contains FeO and CoO along with MnO. The compositions of the oxide phase above Fe-Co-Mn-O melts are calculated. When the cobalt and manganese contents in the melts increase, the mole fraction of manganese oxide increases, and it approaches 1 in the case of pure cobalt. The dependences of the oxygen solubility in the melts on the cobalt and manganese contents are calculated. The deoxidizing capacity of manganese increases substantially with increasing cobalt content in the melt. The curves of oxygen solubility in Fe-Co melts have minima, whose values shift toward low manganese content in a melt. The manganese contents are determined at the minimum points in the oxygen solubility curves, and the corresponding minimum oxygen contents are found.     

Thermodynamics of the oxygen solutions in the aluminum-containing Ni–Co melts

A thermodynamic analysis of the oxygen solutions in the aluminum-containing Ni–Co melts has been performed. The equilibrium constants of reactions of aluminum deoxidation of nickel-cobalt melts, the activity coefficients at infinite dilution, and the interaction parameters for the melts differing in composition at 1873 K have been determined for the first time. The dependences of the oxygen solubility on the cobalt and aluminum contents in the melts are calculated. The deoxidizing capacity of aluminum slightly varies as the cobalt content in a melt increases to 20%; at higher cobalt contents in the melts, it increases substantially. The aluminum contents at the minima in the oxygen solubility curves and the oxygen contents corresponding to the aluminum contents have been determined.     

Thermodynamics of Oxygen Solutions in Ni–Cr Melts Containing Aluminum

The influence of aluminum on the solubility of oxygen in Ni–Cr melts is considered on the basis of thermodynamic analysis. Very low aluminum concentrations have practically no influence on the oxygen concentration in the melt, which is determined by the chromium content. When the aluminum content exceeds 0.01%, it determines the solubility of oxygen in the melt, in all cases. The minimum oxygen concentration corresponds to about 0.2% Al. With increase in chromium content in the melt, the minimum oxygen concentration increases. It is 2 × 10^–3%, 7 × 10^–3%, and 10^–2% for nickel alloys with 10%, 20%, and 30% Cr, respectively.     

X射线荧光光谱法测定铬、钒、钛共存的钛合金中12种元素

采用X射线荧光光谱分析钛合金时, 由于共存元素之间存在严重谱线干扰和基体效应, 使元素含量与谱线强度之间相关性差, 影响测定结果的准确度和精密度, 尤其是铬、钒、钛 3元素共存的钛合金是X射线荧光光谱检测遇到的难题。试验通过利用多套钛合金标准样品制作校准曲线, 选择适合谱线和测试条件, 校正谱线重叠干扰和基体效应的方法有效地解决钛合金中共存元素的干扰, 其中谱线重叠干扰通过测量计算钛元素Kβ线对钒元素Kα线的重叠系数, 钒元素Kβ线对铬元素Kα线的重叠系数来解决。方法已用于钛合金样品中钼、锡、锆、钒、铝、锰、铁、铬、钨、镍、铜、硅共12个主次元素含量的测定, 测定值与化学法测定值相符, 各元素测定结果的相对标准偏差(RSD, n=10)均小于1.0%。方法可供航空用α、β、α+β 3类钛合金中主次元素的检测。     

Thermodynamics of Oxygen Solution in Fe–Ni Melts Containing Boron

Fe–Ni alloys are widely used in engineering today. They are sometimes alloyed with boron. Oxygen is a harmful impurity in Fe–Ni alloys. It may be present in dissolved form or as nonmetallic inclusions. The presence of oxygen in Fe–Ni alloys impairs their performance. Research on the thermodynamics of oxygen solutions in Fe–Ni melts containing boron is of considerable interest in order to improve alloy production. The present work offers a thermodynamic analysis of solutions of oxygen in Fe–Ni melts containing boron. The equilibrium constant of the reaction between boron and oxygen dissolved in the melt in such systems is determined. The activity coefficients at infinite dilution and the interaction parameters in melts of different composition are also calculated. When boron reacts with oxygen in Fe–Ni melts, the oxide phase contains not only B₂O₃ but also FeO and NiO. The mole fractions of B₂O₃, FeO, and NiO in the oxide phase are calculated for different boron concentrations in Fe–Ni melts at 1873 K. For iron melts with low boron content, the mole fraction of boron oxide is ~0.1. With increase in the nickel and boron content in the melts, the boron-oxide content in the oxide phase increases. Its mole fraction is close to one for pure nickel. The solubility of oxygen in Fe–Ni melts is calculated as a function of the nickel and boron content. The deoxidizing ability of the boron improve significantly with increase in nickel content in the melt. The curves of oxygen solubility in Fe?Ni melts containing boron pass through a minimum, which is shifted to higher boron content with increase in nickel content in the melt. The boron content at the minima on the curves of oxygen solubility are determined, as well as the corresponding minimum oxygen concentrations.     

Thermodynamics of the oxygen solutions in chromium-containing Ni–Co melts

A thermodynamic analysis of the oxygen solutions in chromium-containing Ni–Co melts at 1873 K has been performed. The equilibrium constants of reactions between chromium and oxygen, the activity coefficients at infinite dilution, and the interaction parameters for melts differing in composition have been determined. The dependences of the oxygen solubility on the cobalt and chromium contents in the melts are calculated. The deoxidizing capacity of chromium slightly decreases as the cobalt content in the melt increases. The composition dependences of the oxygen solubility in the chromium-containing Ni–Co melts have a minimum, which shifts to a high boron content as the cobalt content in the melts increases. The further increase in the chromium addition leads to an increase in the oxygen content in the melt.     

Effect of zirconium on the oxygen solubility in liquid nickel and Ni–Fe melts

The oxygen solubility in liquid nickel containing zirconium is studied experimentally for the first time at 1873 K. The equilibrium constants of the reaction of interaction between zirconium and oxygen dissolved in liquid nickel, the interaction parameters characterizing these solutions, and the zirconium activity coefficient in nickel at infinite dilution are found. The equilibrium constants of the reaction of interaction between zirconium and oxygen dissolved in the melt, the Gibbs energy of the reaction of interaction between zirconium and oxygen, and the interaction parameters characterizing these solutions are calculated at 1873 K for a wide composition range of Ni–Fe alloys. The oxygen solubility in various Ni–Fe melts containing zirconium is found at 1873 K. The deoxidizing capacity of zirconium increases as the iron content increases to 30% and decreases at higher iron content in the melt. This can be explained by the fact that an increase in the iron content lead to, on the one hand, a strengthening of the bonding forces of oxygen atoms in a melt and, on the other hand, to a significant weakening of the bonding forces of zirconium atoms with the base metal.     

Thermodynamics of oxygen solutions in nickel melts containing aluminum and titanium

Thermodynamic analysis of oxygen solutions in nickel melt shows that, as aluminum and titanium are added to the melt, the solubility of oxygen decreases. However, after reaching 0.205% Al and 0.565% Ti, the oxygen concentration in the melt begins to rise with increase in the Al and Ti content. The minimum oxygen concentrations in the reduction of nickel melt by aluminum (1.44 × 10^–4% O) and titanium (2.98 × 10^–4% O) are determined. On that basis, we may propose the optimal approach to alloying nickel melts with aluminum and titanium. First, the melt is reduced by adding sufficient aluminum to minimize the oxygen concentration in the melt (~0.2% Al). Then the oxide formed is removed, so as to prevent repeated oxidation of the melt. Finally, the melt is alloyed with aluminum and titanium to obtain the required alloy composition.     

电感耦合等离子体原子发射光谱法测定核级锆合金中17种常量及痕量元素

使用电感耦合等离子体原子发射光谱法对核级锆合金中4种常量元素及13种痕量元素进行测定。通过用高纯海绵锆及主合金元素进行基体匹配和选择合适的光谱线作被测元素分析线,成功地测定了核级锆合金中常量元素锡、铌、铁、铬和痕量元素铝、钴、铜、钼、镁、锰、镍、铅、硅、钽、钛、钒、钨。对NIST的360b锆合金中锡、铁、铬、镍的测定,其测定结果与标准物质证书给出的标准值相一致。对核级锆合金进行加标回收试验,结果表明,除钽的回收率偏低和铝、铅的回收率偏高外,铌、钴、铜、钼、镁、锰、硅、钛、钒、钨的回收率在92%～108%之间。本法的测定结果稳定,3天测定结果的相对标准偏差（RSD）均在6%以下,能满足西屋认证标准（RSD＜10%）的要求。     

电感耦合等离子体原子发射光谱法测定铁矿石中16种元素

准确、快速地测定铁矿中各种杂质元素含量,对铁矿石质量判定具有重要意义。试验采用“酸溶-碱熔回渣”的方法消解样品,先用硝酸、盐酸溶解样品,再过滤,滤渣及滤纸灰化后再用碳酸钠-硼酸混合熔剂熔融,溶液中的总固体溶解量(TDS)为2.5mg/mL。采用基体匹配法绘制校准曲线消除基体效应的影响,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌等16种元素。各待测元素校准曲线的线性相关系数均大于0.999;方法检出限为0.00018%~0.034%。实验方法用于2个铁矿石实际样品中铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌的测定,结果的相对标准偏差(RSD,n=8)为0.40%~9.8%;按照实验方法测定4个铁矿石标准样品,测定值与认定值相吻合;测定4个铁矿石生产样品中铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌,测定值与GB/T 6730系列标准方法测定值相吻合。     

电感耦合等离子体原子发射光谱法测定铁矿石中16种元素

准确、快速地测定铁矿中各种杂质元素含量,对铁矿石质量判定具有重要意义。试验采用“酸溶-碱熔回渣”的方法消解样品,先用硝酸、盐酸溶解样品,再过滤,滤渣及滤纸灰化后再用碳酸钠-硼酸混合熔剂熔融,溶液中的总固体溶解量(TDS)为2.5mg/mL。采用基体匹配法绘制校准曲线消除基体效应的影响,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌等16种元素。各待测元素校准曲线的线性相关系数均大于0.999;方法检出限为0.00018%~0.034%。实验方法用于2个铁矿石实际样品中铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌的测定,结果的相对标准偏差(RSD,n=8)为0.40%~9.8%;按照实验方法测定4个铁矿石标准样品,测定值与认定值相吻合;测定4个铁矿石生产样品中铝、砷、钙、铬、铜、钾、镁、锰、镍、磷、铅、硅、锡、钛、钒、锌,测定值与GB/T 6730系列标准方法测定值相吻合。     

Solubility of oxygen in carbon-bearing Fe-Ni melts

Oxygen solutions in carbon-bearing Fe-Ni melts are analyzed thermodynamically. The equilibrium oxygen concentrations in Fe-Ni alloys in the presence of carbon have been determined for the first time over a wide composition range and a wide range of the partial pressures of carbon mono-and dioxides. As the carbon concentration increases, the oxygen concentration decreases in melts of all compositions. As the nickel content in the melt increases, the equilibrium oxygen concentration decreases at the same carbon concentration. The difference in the oxygen concentrations in iron and nickel at the same carbon concentration is almost two orders of magnitude, which can be explained by the substantial weakening of the bonding forces of oxygen in the melt and the less pronounced weakening of the bonding forces of carbon atoms with increasing nickel content. The oxygen solubility curves pass through a minimum, whose position changes with the nickel content from 2.443% C for pure iron to 2.842% C for pure nickel. The solubility of oxygen in a Fe-40% Ni melt is experimentally studied at various carbon contents. The experimental results agree well with the calculated data.     

Thermodynamics of the oxygen solutions in boron-containing Fe–Co melts

A thermodynamic analysis of the oxygen solutions in boron-containing Fe–Co melts has been performed. The equilibrium constant of reaction between boron and oxygen, which are dissolved in iron–cobalt melts; the activity coefficients at infinite dilution; and the interaction parameters for melts differing in composition have been determined. The oxide phase formed in the Fe–Co melts containing boron and oxygen comprises FeO and CoO along with the B₂O₃ phase. The oxide phase compositions over Fe–Co–B–O melts are calculated. As the cobalt and boron contents in the melts increase, the mole fraction of boron oxide increases; in the case of pure cobalt, it is close to unity. The dependences of the oxygen solubility on the cobalt and boron contents in the melts are calculated. The deoxidizing capacity of boron substantially increases as the cobalt content in a melt increases. The composition dependences of the oxygen solubility in boron-containing Fe–Co melts have a minimum, which shifts to a low boron content as the cobalt content in the melts increases. The boron contents corresponding to the minimum in the oxygen solubility curves and the minimum oxygen concentrations corresponding to the boron contents are determined.