· Lanthanum Impact On TZC Phase Composition - Molybdenum Alloy Products

Lanthanum Impact On TZC Phase Composition

Does lanthanum has any effect on TZC alloy phase composition?

X-ray diffraction powder of electrolytic extraction analysis of a second phase, the results show that without the addition of lanthanum (La) of the alloy, the main phase is a second TiC and ZrO2; in Canada lanthanum (La) of the alloy , the second phase is a major La2Zr2O7 and MC, namely (Ti, Zr, Mo) C. La2Zr2O7 wherein the face-centered cubic structure with a lattice constant of 10.793 people, MC is face-centered cubic structure similar to the lattice constant of the TiC was dissolved in a small amount of TiC and Mo and Zr composition.

TEM analysis and X-ray analysis results were consistent. However, TEM found in the plus lanthanum (La) in the alloy, carbide phase is essentially symbiotic with La2Zr2O7 phase, and the individual phase rarely MC carbides, in particular, containing lanthanum (La) t higher alloys, this phenomenon is more obvious, this symbiosis with the core of the La2Zr2O7, the other part is mainly carbide.

The second phase of the powder of electrolytic extraction of elemental analysis, the results shown in Table 1, in which Zr and lanthanum (La) containing t in Table 1, almost the total alloy content of the same, that Minga human Zr and lanthanum (La ) almost all present in the second phase formed mainly of La2Zr2O, the composite oxide. Lanthanum (La) in the alloy in oxide form, which is determined by thermodynamic and kinetic conditions.

Table1 the second phase of the main chemical components (%)

Sample No. Ti Zr Mo lanthanum (La)
TZC-0 0.53 0.21 0.45 -
TZC-5 0.45 0.22 0.58 0.39
TZC-9 0.45 0.22 0.45 0.63

Note: Due to the extracted second phase is less, so there is no oxygen and carbon content analysis.

Lanthanum (La) oxide reacts with oxygen free energy change for the reaction system, the alloy all possible reactions, the negative maximum, indicating lanthanum (La) most likely to react with oxygen, followed by Zr. In the alloy material, the oxygen content (oxygen content of platinum powder material 0.17%), therefore, lanthanum (La) in the alloy in the form of an oxide. In addition lanthanum alloys, lanthanum (La) and Zr composite oxide formation, rather than a separate La2O3 and ZrO2, which may be based composite state exists there is more stable than the individual.

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