TY - JOUR
T1 - High-temperature strength and plastic deformation behavior of niobium diboride consolidated by spark plasma sintering
AU - Demirskyi, Dmytro
AU - Solodkyi, Ievgen
AU - Nishimura, Toshiyuki
AU - Sakka, Yoshio
AU - Vasylkiv, Oleg
N1 - Funding Information:
This study was partially financial supported by the Grant-in-Aid for Scientific Research B (No.15H04163) from JSPS. The authors wish to express their appreciation to Dr. H. Kanai (NIMS) for kindly providing access to the SEM equipment.
Publisher Copyright:
© 2017 The American Ceramic Society
PY - 2017/11
Y1 - 2017/11
N2 - Bulk niobium diboride ceramics were consolidated by spark plasma sintering (SPS) at 1900°C. SPS resulted in dense specimens with a density of 98% of the theoretical density and a mean grain size of 6 μm. During the SPS consolidation, the hexagonal boron nitride (h-BN) was formed from B2O3 on the powder particle surface and residual adsorbed nitrogen in the raw diboride powder. The room-temperature strength of these NbB2 bulks was 420 MPa. The flexural strength of the NbB2 ceramics remained unchanged up to 1600°C. At 1700°C an increase in strength to 450 MPa was observed, which was accompanied by the disappearance of the secondary h-BN phase. Finally, at 1800°C signs of plastic deformation were observed. Fractographic analysis revealed a number of etching pits and steplike surfaces suggestive of high-temperature deformation. The temperature dependence of the flexural strength of NbB2 bulks prepared by SPS was compared with data for monolithic TiB2, HfB2 and ZrB2. Our analysis suggested that the thermal stresses accumulated during SPS consolidation may lead to additional strengthening at elevated temperatures.
AB - Bulk niobium diboride ceramics were consolidated by spark plasma sintering (SPS) at 1900°C. SPS resulted in dense specimens with a density of 98% of the theoretical density and a mean grain size of 6 μm. During the SPS consolidation, the hexagonal boron nitride (h-BN) was formed from B2O3 on the powder particle surface and residual adsorbed nitrogen in the raw diboride powder. The room-temperature strength of these NbB2 bulks was 420 MPa. The flexural strength of the NbB2 ceramics remained unchanged up to 1600°C. At 1700°C an increase in strength to 450 MPa was observed, which was accompanied by the disappearance of the secondary h-BN phase. Finally, at 1800°C signs of plastic deformation were observed. Fractographic analysis revealed a number of etching pits and steplike surfaces suggestive of high-temperature deformation. The temperature dependence of the flexural strength of NbB2 bulks prepared by SPS was compared with data for monolithic TiB2, HfB2 and ZrB2. Our analysis suggested that the thermal stresses accumulated during SPS consolidation may lead to additional strengthening at elevated temperatures.
KW - high-temperature strength
KW - niobium diboride
KW - spark plasma sintering
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U2 - 10.1111/jace.15048
DO - 10.1111/jace.15048
M3 - Article
AN - SCOPUS:85022333924
VL - 100
SP - 5295
EP - 5305
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
SN - 0002-7820
IS - 11
ER -