TY - JOUR
T1 - Effect of Nb/W Ratio on Fe2 (Nb, W) Laves Phase Formation in Fe-Cr-Al-Nb-W Alloy
AU - Yamagata, Ryosuke
AU - Yoshimi, Kyosuke
PY - 2016
Y1 - 2016
N2 - Laves phases may be one of effective reinforcements at higher temperature for creep-resistant ferritic steels. In this study, the effect of Nb/Wratio on crystallization and precipitation behavior of Fe2 (Nb,W) Laves phase was investigated for Fe-Cr-Al-Nb-Wferritic alloys. Fe-9Cr-6.5Al-10 (Nb,W) (at-) alloys were prepared by a conventional arc-melting technique. In the As- cast condition, the 10 at- Nb alloy was entirely composed of a eutectic phase of ferrite and Fe2Nb. By substitutingWfor a part of Nb, the microstructure was changed to the combination of the primary ferrite and the eutectic of ferrite and Fe2 (Nb, W). The microstructural change indicates that the composition shifted from eutectic to hypo-eutectic with increasing the W/(Nb+W) ratio in the alloy. For the 10 at- W alloy, there was no Laves phase in the as-cast microstructure. However, a number of Laves phase precipitates were observed inside grains after heat-treatment at 1000°C. The volume fraction of Laves phases decreased with increasing the W/(Nb+W) ratio in the alloy since the solubility limit of W in the ferritic matrix is higher than that of Nb at 1000°C. Therefore, the volume fraction and morphology are controllable by the Nb/W ratio in the Fe-Cr-Al-Nb-W alloy.
AB - Laves phases may be one of effective reinforcements at higher temperature for creep-resistant ferritic steels. In this study, the effect of Nb/Wratio on crystallization and precipitation behavior of Fe2 (Nb,W) Laves phase was investigated for Fe-Cr-Al-Nb-Wferritic alloys. Fe-9Cr-6.5Al-10 (Nb,W) (at-) alloys were prepared by a conventional arc-melting technique. In the As- cast condition, the 10 at- Nb alloy was entirely composed of a eutectic phase of ferrite and Fe2Nb. By substitutingWfor a part of Nb, the microstructure was changed to the combination of the primary ferrite and the eutectic of ferrite and Fe2 (Nb, W). The microstructural change indicates that the composition shifted from eutectic to hypo-eutectic with increasing the W/(Nb+W) ratio in the alloy. For the 10 at- W alloy, there was no Laves phase in the as-cast microstructure. However, a number of Laves phase precipitates were observed inside grains after heat-treatment at 1000°C. The volume fraction of Laves phases decreased with increasing the W/(Nb+W) ratio in the alloy since the solubility limit of W in the ferritic matrix is higher than that of Nb at 1000°C. Therefore, the volume fraction and morphology are controllable by the Nb/W ratio in the Fe-Cr-Al-Nb-W alloy.
KW - Eutectic reaction
KW - Ferritic steel
KW - Laves phase
KW - Microstructure formation
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U2 - 10.2320/jinstmet.J2016027
DO - 10.2320/jinstmet.J2016027
M3 - Article
AN - SCOPUS:84989183230
SN - 0021-4876
VL - 80
SP - 646
EP - 654
JO - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
JF - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
IS - 10
ER -