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大过冷度下Ni54.6Pd45.4合金的再结晶
Recrystallization for Ni54.6Pd45.4 Alloy under Large Degree of Undercooling
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- DOI:
- 作者:
- 李云华
- 作者单位:
- 苏州大学机电工程系,江苏 苏州 215021
- 关键词:
- 淬火;再结晶;显微组织;过冷度
Quenching; Recrystallization; Microstructure; Undercooling
- 摘要:
- 通过将不同冷却阶段的试样淬火,研究了再结晶诱发的块状过冷Ni54.6Pd45.4
合金的组织演化。结果表明,当过冷度大于临界过冷度时,由于再结晶引起的晶粒细化起始
于快速凝固阶段结束之时,并在随后的冷却过程中发展。再结晶初始阶段由于晶核形成,导
致晶粒尺寸降低。随后,由于晶粒的相互吞并长大占主导地位,晶粒尺寸增加。随着凝固前
过冷度的增加,快速凝固的枝晶骨架间的变形程度增加,再辉温度在高温阶段停留的时间也
降低。最终使得再结晶晶粒尺寸下降。
Structure evolution driven by recrystallization in the bulk undercooled Ni54
.6Pd45.4 alloy was investigated by quenching the sample at different coo
ling stages. The results show that recrystallization of the solid beyond the cri
tical undercooling for grain refinement starts at the end of rapid solidificatio
n, and develops during slow solidification and subsequent cooling process. At th
e initial stage of recrystallization, nuclei successively formed in the sample,
And the grain size decrease. At the later stage, annexation of grains dominates
the recrystallization process, due to which the number of grain size increases.
As undercooling before solidification increases, the deformation degree in the r
apidly solidified dendrite net rises, and the recalescence temperature as well a
s the duration at high temperature decreases. Consequently the recrystallization
grain size structure decreases.