Effect of mechanical alloying on the structure and properties of NbCr2 Laves phase fabricated by hot pressing

Nie, Xiao-wu; Lu, Shi Qiang; Wang, K.L.

doi:10.1016/j.powtec.2007.09.006

Cited by 15 publications

(8 citation statements)

References 11 publications

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“…The data is given in Table 4 together with the average measured hardness values from Table A1 in the Appendix A. For these calculations the hardness of 900 HV was used for the NbCr 2 Laves phase [40,41,42]. The calculated hardness values that are close to the measured ones are given in bold numbers.…”

Section: Discussionmentioning

confidence: 96%

A Study of the Effects of Hf and Sn on the Microstructure, Hardness and Oxidation of Nb-18Si Silicide Based Alloys without Ti Addition

2018

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The paper presents the results of an experimental study of large (≈0.6 kg) arc melted buttons of four Ti free Nb-silicide based alloys with Sn addition with nominal compositions (at.%) Nb-18Si-5Hf-5Sn (EZ1), Nb-18Si-5Al-5Sn (EZ7), Nb-18Si-5Cr-5Hf-5Sn (EZ3) and Nb-18Si-5Al-5Hf-5Sn (EZ4). The alloys were studied in the as-cast and heat treated conditions. In all the alloys there was macrosegregation of Si (MACSi). Among the single element additions Hf had the weakest and Sn the strongest effect on MACSi. The simultaneous presence of Cr and Hf in the alloy EZ3 had the strongest effect on MACSi. In all the alloys the βNb5Si3 was the primary phase and was present after the heat treatment(s), the Nb3Si silicide was suppressed and the A15-Nb3Sn intermetallic was stable. The Nbss was not stable in the alloys EZ7 and EZ4 and the C14-NbCr2 Laves phase was stable in the alloy EZ3. Very Hf-rich Nb5Si3 was stable in the alloy EZ4 after prolonged heat treatments. Eutectics were observed in all the alloys. These were binary eutectics in the alloys EZ1 and EZ7, where respectively they consisted of the Nbss and βNb5Si3, and βNb5Si3 and A15-Nb3Sn phases. Most likely ternary eutectics consisting of the Nbss, C14-NbCr2 and βNb5Si3, and Nbss, βNb5Si3 and A15-Nb3Sn phases were observed, respectively in the alloys EZ3 and EZ4. The addition of Al increased the vol% of the Nb5Si3 and A15-Nb3Sn phases, particularly after the heat treatment(s). The lattice parameter of Nb respectively increased and decreased with the addition of Hf, and Al or Cr and the latter element had the stronger negative effect. Pest oxidation was not suppressed in the alloys of this study.

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Section: Discussionmentioning

confidence: 96%

A Study of the Effects of Hf and Sn on the Microstructure, Hardness and Oxidation of Nb-18Si Silicide Based Alloys without Ti Addition

2018

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“…Cross-section of the oxidized specimens was investigated by SEM. XRD data was collected at a slow scan rate of 0.005 0 /s for the careful determination of average crystallite size and internal strain using Williamson-Hall method and the method is suggested by Ungar et al [17,18].…”

Section: Methodsmentioning

confidence: 99%

High Temperature Oxidation of Cr-25Nb Alloy Synthesized by Mechanical Alloying and Hot Pressing

Nie¹,

Niu²,

Ouyang³

et al. 2009

TOCORRJ

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Cr-25Nb alloy was prepared by mechanical alloying (MA) and hot pressing (HP), and the influences of milling time on the density and oxidation property of samples were investigated. During the studying of the effect of different ball grinding time on oxidation resistance, we discover that the relative density of the Cr-25Nb alloy would increase with the ball grinding time increasing, but when it was oxidized at 1200°C for 5 h in the air, the gain weight rate of the oxidized samples does not only decreased with the ball milling time increasing. In the period of MA 0 to 20 h, the gain weight rate of the oxidized samples reduced with the ball milling time increasing. When the ball milling time further increased, the gain weight rate increased and the oxidation resistance of samples went down. Thus, the oxidation resistance of sample of MA 20 is best. The oxide layer appearance of MA 15 h, MA 20 h, MA 35 h were observed by SEM, respectively. It is found that the oxide layer thickness of specimen of MA 20 hour is thinnest. From the result of EDS and XRD, Cr 2 O 3 was formed on the outer oxide layer. However, the oxides in the inner layer were mainly Cr 2 O 3 and CrNbO 4 .

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“…[14][15][16] investigated the mechanical properties of the pure Cr 2 Nb, but did not mention the crystal structure of Cr 2 Nb with the additive element X. Ref. [17] investigated the mechanical properties of Cr 2 Nb with Ni, but did not present the crystal structure of Cr 2 Nb with Ni. That is to say, Nie claims ''for C15 Cr 2 Nb the Cr 3 XNb 2 or Cr 3 XNb is face-centered-cubic and a ¼ b ¼ c'' that is speculative.…”

Section: Our Repliesmentioning

confidence: 99%

“…Cr 50 V 17 [6,19,20]. The results show that Mo can decrease strength of Cr 2 Nb, while V and W increase its strength.''…”

Section: Our Repliesmentioning

confidence: 99%

Response to Comment on “Effects of X (V, W, Mo, Hf, Ta, Zr) additions on the ideal cleavage fracture of Cr2Nb: First-principles determination”

2010

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Effect of mechanical alloying on the structure and properties of NbCr2 Laves phase fabricated by hot pressing

Cited by 15 publications

References 11 publications

A Study of the Effects of Hf and Sn on the Microstructure, Hardness and Oxidation of Nb-18Si Silicide Based Alloys without Ti Addition

A Study of the Effects of Hf and Sn on the Microstructure, Hardness and Oxidation of Nb-18Si Silicide Based Alloys without Ti Addition

High Temperature Oxidation of Cr-25Nb Alloy Synthesized by Mechanical Alloying and Hot Pressing

Response to Comment on “Effects of X (V, W, Mo, Hf, Ta, Zr) additions on the ideal cleavage fracture of Cr2Nb: First-principles determination”

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