Effects of Si, W and W–Mo on isothermal oxidation behaviors of Nb/Nb5Si3 in situ composites at high temperature

Xiong, Bangshu; Cai, Chunhua; Wan, Hong; Zheng, Yong

doi:10.1016/j.jallcom.2009.06.136

Cited by 28 publications

(6 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the depth of X-ray penetration increases with increasing γ, it is suggested that the former two oxides were formed throughout the scale, and the latter two oxides were formed at a later stage. Thus, Nb and Ti had reacted stronger with oxygen than Si and Ge, which is in agreement with [47,48,49,50,51,52]. This was supported by the difference in the compositions of the Nb ss between the diffusion zone and the bulk.…”

Section: Discussionsupporting

confidence: 82%

“…The oxidation resistance of Nb-silicide based alloys is sensitive to the vol % of Nb ss [47,48,49]. The Ge addition in the ZF series alloys resulted to lower vol% of the Nb ss in ZF4 (15.4 ± 3.1 %) [29], ZF5 (16.4 ± 3.8%) [30] and ZF6 (17.3 ± 3.5%) [31] compared with the KZ series alloys Nb-24Ti-18Si-5Cr (48–55% [47]), Nb-24Ti-18Si-5Al-5Cr (48–55% [47]), Nb-24Ti-18Si-6Ta-5Al-5Cr (50–59% [47]), and the JG series alloys Nb-24Ti-18Si-5Al-5Cr-5Mo (34.2% [50]), Nb-24Ti-18Si-5Al-5Cr-2Mo (35.9% [50]), and Nb-24Ti-18Si-5Al-5Cr-5Hf-2Mo (39.1% [24]).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Ge Addition on the Oxidation of Nb-24Ti-18Si Silicide Based Alloys

Tsakiropoulos

2019

Materials

View full text Add to dashboard Cite

In this paper, we report research about the isothermal oxidation in air at 800 and 1200 °C for 100 h of the as-cast alloys (at.%) Nb-18Si-5Ge (ZF1), Nb-18Si-10Ge (ZF2), Nb-24Ti-18Si-5Ge (ZF3), Nb-24Ti-18Si-5Cr (ZF4), Nb-24Ti-18Si-5Al (ZF5), Nb-24Ti-18Si-5Al-5Cr-5Ge (ZF6), and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (ZF9), the microstructures of which were reported in previous publications. Only the alloys ZF1, ZF2, and ZF3 suffered from pest oxidation at 800 °C. The Ge addition substantially improved the oxidation resistance of the other alloys both at 800 °C and 1200 °C, which followed parabolic kinetics at 800 °C and in the early stages at 1200 °C and linear kinetics at longer times, where there was spallation of the scales. The Nb2O5 and TiNb2O7 oxides were formed in the scales of the alloys ZF4, ZF5, ZF6, and ZF9 at 800 °C and 1200 °C, the GeO2 was observed in all scales and the SiO2 in the scales of the alloys ZF4 and ZF5, the CrNbO4 in the scales of the alloys ZF4, ZF6, and ZF9 and the AlNbO4 in the scales of the alloys ZF5, ZF6, and ZF9. Diffusion zones were formed below the scale/substrate interface only in the alloys ZF4 and ZF5 where the Nbss and Nb5Si3 were contaminated by oxygen. However, these phases were not contaminated by oxygen in the bulk of the alloys ZF4, ZF5, ZF6, and ZF9. The alloys ZF9 and ZF6 exhibited the best oxidation behaviour at 800 °C and 1200 °C, respectively. The alloys were compared with Nb-silicide based alloys of similar compositions without Ge and Hf additions and the alloy ZF9 with refractory metal High Entropy Alloys. Compared with the former alloys, the addition of Ge reduced the vol % of the Nbss. Compared with the latter alloys, the superior oxidation behaviour of the alloy ZF9 was attributed to its higher and lower values respectively of the parameters δ and VEC.

show abstract

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

The Effect of Ge Addition on the Oxidation of Nb-24Ti-18Si Silicide Based Alloys

Tsakiropoulos

2019

Materials

View full text Add to dashboard Cite

show abstract

“…The material exhibits brittle behavior when B/G b 1.75, and vice versa, a material demonstrates ductile when B/G N 1.75. From Table 2, the calculated B/G ratio of Nb 5 Si 3 (1.54) is lower than 1.75, implying that it exhibits intrinsic brittle behavior, which is consistent with the experimental result [27][28][29]. It is clear that the calculated B/G ratio of Nb -va1 , Nb -va2 and Si -va2 is lower than 1.75, but the calculated B/G ratio is gradually close to 1.75.…”

Section: Mechanical Propertiessupporting

confidence: 84%

Vacancy induced brittle-to-ductile transition of Nb5Si3 alloy from first-principles

et al. 2015

View full text Add to dashboard Cite

“…Research has ascertained the key role of specific alloying additions for meeting property goals in Nb-silicide-based alloys [ 3 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. RM additions are indispensable for strength and creep, simple metal and metalloid element (SMME) and transition metal (TM) additions are needed for oxidation resistance and TMs and SMMEs are crucial for toughness (RM = Mo, Ta, W, SMME = Al, B, Ge, Si, Sn, TM = Cr, Hf, Ti) [ 1 , 20 , 21 , 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

On the Microstructure and Properties of Nb-18Si-6Mo-5Al-5Cr-2.5W-1Hf Nb-Silicide Based Alloys with Ge, Sn and Ti Additions (at.%)

2020

View full text Add to dashboard Cite

We studied the microstructures and isothermal oxidation of the Nb-silicide-based alloys Nb-11.5Ti-18Si-5Mo-2W-4.9Sn-4.6Ge-4.5Cr-4.7Al-1Hf (JZ4) and Nb-21Ti-18Si-6.7Mo-1.2W-4.4Sn-4.2Ge-4Cr-3.7Al-0.8Hf (JZ5), calculated their average creep rate for the creep goal conditions of T = 1200 °C and σ = 170 MPa, and compared properties of the two alloys with those of other refractory metal (RM) complex concentrated alloys (RCCAs). Both alloys had a density less than 7.3 g/cm3 and lower than the density of multiphase bcc solid solution + M5Si3 silicide RCCAs. There was macrosegregation of Si in both alloys, which had the same phases in their as-cast microstructures, namely βNb5Si3, αNb5Si3, A15-Nb3X (X = Al, Ge, Si, Sn), TM5Sn2X (X = Al, Ge, Si), C14-Cr2Nb, but no solid solution. After heat treatment at 1500 °C for 100 h, a low volume fraction of a W-rich (Nb, W)ss solid solution was observed in both alloys together with βNb5Si3, αNb5Si3 and A15-Nb3X but not the TM5Sn2X, whereas the Laves phase was observed only in JZ4. At 800 °C, both alloys did not pest, and there was no spallation of their scales at 1200 °C. At both temperatures, both alloys followed parabolic oxidation kinetics and their weight changes were lower than those of Ti-rich Nb-silicide-based alloys. The oxidation of both alloys was superior to that of other RCCAs studied to date. For each alloy the Si macrosegregation, volume fraction of solid solution, chemical composition of solid solution and Nb5Si3, and weight changes in isothermal oxidation at 800 and 1200 °C that were calculated using the alloy design methodology NICE agreed well with the experimental results.

show abstract

Effects of Si, W and W–Mo on isothermal oxidation behaviors of Nb/Nb5Si3 in situ composites at high temperature

Cited by 28 publications

References 19 publications

The Effect of Ge Addition on the Oxidation of Nb-24Ti-18Si Silicide Based Alloys

The Effect of Ge Addition on the Oxidation of Nb-24Ti-18Si Silicide Based Alloys

Vacancy induced brittle-to-ductile transition of Nb5Si3 alloy from first-principles

On the Microstructure and Properties of Nb-18Si-6Mo-5Al-5Cr-2.5W-1Hf Nb-Silicide Based Alloys with Ge, Sn and Ti Additions (at.%)

Contact Info

Product

Resources

About