Purification of Ti&amp;ndash;Al Alloys by Induction-Heating Floating-Zone Melting and Cold-Crucible Melting in Ultra-High Vacuum

Nakajima, Taira; Morimoto, Y.; Takaki, S.; Abiko, K.

doi:10.2320/matertrans1989.41.22

Cited by 9 publications

(23 citation statements)

References 6 publications

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“…If the analysis of oxygen in Ti-Al alloys is performed by the generally used method, the value obtained is lower than the true value. 6) The purity of the alloy, which was more than 99.994 mass% after analysis of 40 elements, includes the values of the detection limit for all elements.…”

Section: Methodsmentioning

confidence: 99%

“…Concerning our current research series, Nakajima et al 6) reported that a high-purity Ti-Al alloy containing only 13 ppm oxygen was prepared by floating-zone melting under ultra-high vacuum (UHV); however, the volume was too small to measure its mechanical properties. Next, they pro- * Present address: Nikko Materials Co., Ltd., Kitaibaraki 319-1535, Japan.…”

Section: Introductionmentioning

confidence: 99%

“…duced an 800 g ingot of Ti-Al alloy by cold-crucible induction melting (CCIM) in UHV; 6) however, the ingot contained 85 ppm oxygen, and metallic impurities in the ingot were not analyzed. Recently we reported on the preparation by coldcrucible induction melting in UHV 7) of a 1 kg ultrahigh-purity Ti-45 mol%Al (Ti-45Al) alloy of more than 99.994 mass% purity after analysis of 40 elements.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

et al. 2002

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An ultrahigh-purity Ti-45 mol%Al alloy ingot was isothermally hot-pressed along each of the X, Y and Z coordinates at 1473 K. The hot-pressed ingot consisted mainly of very fine recrystallized grains, with an average size of 5 µm. The mechanical properties of this finegrained Ti-Al alloy were examined by tensile test at 293 K, 823 K, and 923 K at strain rate of 1.1 × 10 −4 s −1 in a vacuum of 1.3 × 10 −3 Pa. The ductile-brittle transition temperature (DBTT) was determined by the tensile tests and scanning electron microscope observation of the fracture surfaces of the samples. This ultrahigh-purity Ti-45 mol%Al alloy showed the following excellent high-temperature mechanical properties: (1) The 0.2% proof strength was 486 MPa and elongation at 923 K was 45%. (2) The DBTT was 870 K, which is about 200 K lower than that of conventional binary Ti-Al alloys with similar composition.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

et al. 2002

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“…In our current research, Nakajima et al [4] reported that a high-purity Ti-Al alloy containing 45 mass ppm oxygen was prepared by arc melting in argon; however, oxygen did not decrease any more by melting the alloy in hydrogen in induction-heating floating-zone melting (FZM) furnace. Furthermore, Nakajima et al [5] reported that a high-purity Ti-Al alloy containing only 13 mass ppm oxygen was obtained by FZM in ultrahigh vacuum (UHV). It was, however, too small to measure its mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Purification of Ti-Al Alloy by Cold-Crucible Induction Melting in Ultrahigh Vacuum

Kawarada

Harima

Takaki

et al. 2002

phys. stat. sol. (a)

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In order to investigate the effect of ultrahigh vacuum melting on the purification of Ti-Al alloy, a 1 kg ultrahigh-purity Ti-45 mol% Al alloy ingot of more than 99.9940 mass% purity after analysis of 40 elements was prepared by cold-crucible induction melting (CCIM) in argon and in ultrahigh vacuum. High-purity aluminium of 99.9986 mass% purity and high-purity titanium of 99.985 mass% purity were used as starting materials. The impurity analysis was done using quadrupole residualgas analysis, chemical analysis, and glow-discharge mass spectrometry (GDMS) analysis. The concentration of gaseous impurities in the ingot was 51 mass ppm (O ¼ 35, N ¼ 11, C ¼ 5, S < 0.5). As a result of GDMS analysis of 36 metallic elements in the ingot, the total amount of metallic impurities was below 8.7 mass ppm, exclusive of 23 elements below their detection limits. The cold-crucible induction melting in UHV is effective in preparing an ultrahigh-purity Ti-Al alloy ingot containing low concentrations of gaseous and metallic impurities.

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“…Since then we have published many papers [14][15][16] on preparation, trace analysis, and characteristic properties of ultrahigh-purity metals and alloys. We prepared, for example, ultrahighpurity iron ingot 10 kg in weight of higher than 99.9988% purity after the analysis of 33 elements and containing the concentration of C þ N þ O þ S of less than 3.4 mass ppm using the CCIM furnace, 17) high-purity Fe-Cr system alloys, 18,19) high-purity Ti-Al alloys, 20) and so on. The purpose of the present paper is to investigate the effect of CCIM under ultrahigh vacuum of 10 À7 Pa on the purification of high-purity nickel, cobalt and titanium due to the removal of gaseous impurities and thus to establish a new purification procedure to obtain high-purity these metals even on the scale of one to ten kg in weight.…”

Section: Introductionmentioning

confidence: 99%

Purification of Cobalt, Nickel, and Titanium by Cold-Crucible Induction Melting in Ultrahigh Vacuum

Takaki

Abiko

2006

Mater. Trans.

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Three separate charges of cobalt 9.2 kg in weight, 3.0 kg nickel and 1.6 kg titanium have been melted in ultrahigh vacuum (UHV) using cold-crucible induction melting (CCIM) furnace, in which UHV of better than 1 Â 10 À7 Pa is attainable. The effects of CCIM in UHV on the purification of these metals due to the removal of gaseous impurities, and the characteristics of CCIM in UHV have been investigated by the analysis of the melting conditions such as the total pressure and the mass spectra of gases during CCIM, and analytical results of these ingots. CCIM in the present UHV degree and quality is found to be very effective for the purification due to the removal of gaseous impurities in cobalt and nickel, in particular, for the decrease in oxygen, and very important for melting of ultrahigh-purity titanium without any contamination by gaseous impurities, in particular, oxygen.

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Purification of Ti–Al Alloys by Induction-Heating Floating-Zone Melting and Cold-Crucible Melting in Ultra-High Vacuum

Cited by 9 publications

References 6 publications

Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

Purification of Ti-Al Alloy by Cold-Crucible Induction Melting in Ultrahigh Vacuum

Purification of Cobalt, Nickel, and Titanium by Cold-Crucible Induction Melting in Ultrahigh Vacuum

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