TY - JOUR
T1 - Microstructure evolution of peritectic Nd14Fe79B7 alloy during directional solidification
AU - Zhong, Hong
AU - Li, Shuangming
AU - Lü, Haiyan
AU - Liu, Lin
AU - Zou, Guangrong
AU - Fu, Hengzhi
PY - 2008/7/1
Y1 - 2008/7/1
N2 - Bridgman type directional solidification experiments were carried out in Nd14Fe79B7 alloy. Microstructure evolutions along with growth velocities were investigated. At low velocities from 1 to 200 μm/s, the microstructures consisted of leading α-Fe dendrites and peritectic Nd2Fe14B phase in the interdendritic region. At medium velocities of 425 and 500 μm/s, an incomplete banded structure formed, containing circles of α-Fe/Nd2Fe14B-Nd2Fe14B dendrites. At high velocities of 1, 3 and 5 mm/s, a transition from γ-Fe dendrites to Nd2Fe14B dendrites occurred. Phase selection phenomena were theoretically studied using the extremum criterion which assumes growth-controlled phase selection. The theoretical results are in agreement with experimental results at low velocities of 1-200 μm/s and high velocities of 3 and 5 mm/s. The incomplete dendritic bands at 425 and 500 μm/s were explained by nucleation of Nd2Fe14B phase at the γ-Fe dendritic interface, and growth competition between γ-Fe and the nucleated Nd2Fe14B phase. Phase transition from γ-Fe to Nd2Fe14B at 1 mm/s was interpreted by abundant nucleation and quick growth of Nd2Fe14B phase at the γ-Fe dendritic interface.
AB - Bridgman type directional solidification experiments were carried out in Nd14Fe79B7 alloy. Microstructure evolutions along with growth velocities were investigated. At low velocities from 1 to 200 μm/s, the microstructures consisted of leading α-Fe dendrites and peritectic Nd2Fe14B phase in the interdendritic region. At medium velocities of 425 and 500 μm/s, an incomplete banded structure formed, containing circles of α-Fe/Nd2Fe14B-Nd2Fe14B dendrites. At high velocities of 1, 3 and 5 mm/s, a transition from γ-Fe dendrites to Nd2Fe14B dendrites occurred. Phase selection phenomena were theoretically studied using the extremum criterion which assumes growth-controlled phase selection. The theoretical results are in agreement with experimental results at low velocities of 1-200 μm/s and high velocities of 3 and 5 mm/s. The incomplete dendritic bands at 425 and 500 μm/s were explained by nucleation of Nd2Fe14B phase at the γ-Fe dendritic interface, and growth competition between γ-Fe and the nucleated Nd2Fe14B phase. Phase transition from γ-Fe to Nd2Fe14B at 1 mm/s was interpreted by abundant nucleation and quick growth of Nd2Fe14B phase at the γ-Fe dendritic interface.
KW - A1. Directional solidification
KW - A1. Morphological stability
KW - A1. Nucleation
KW - A1. Peritectic
KW - A2. Bridgman technique
KW - B1. Rare earth compounds
UR - http://www.scopus.com/inward/record.url?scp=44749094573&partnerID=8YFLogxK
U2 - 10.1016/j.jcrysgro.2008.04.022
DO - 10.1016/j.jcrysgro.2008.04.022
M3 - 文章
AN - SCOPUS:44749094573
SN - 0022-0248
VL - 310
SP - 3366
EP - 3371
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 14
ER -