| 镍基高温合金的正电子湮没研究 | |
| 邓文 | |
| Subtype | 硕士 |
| Thesis Advisor | 龙期威 |
| 1991 | |
| Degree Grantor | 中国科学院金属研究所 |
| Place of Conferral | 中国科学院金属研究所 |
| Abstract | 本文用正电子湮没技术及透射电镜主要研究：形变Ni-Cr-Co高温合金的回复行为：硼对Ni_3Al合金空位型缺陷的影响；氢与多晶Ni_3Al合金中缺陷的相互作用。形变Ni-Cr-Co合金的回复过程主要存在两个阶段：空位回复和位错回复。它的开始再结晶温度在500 ℃左历。经相同形变量冷轧后，Co含量低的合金比Co含量高的合金产生的缺陷多。在随后的退火过程中，前者的位错回复速度比后者的快。Ni-Cr-Co合金的表观再结晶激活能随Co含量的增加而增加。多晶Ni_3Al晶界的开空间比空位和位错的开空间大。在单晶和多晶Ni_3Al合金中加入少量的硼，一部分硼以间隙方式溶解到基体中，另一部分填充到空位型缺陷上。加入的量为1.37at%时，填充饱和。更高的硼会产生更多的缺陷。对多晶NiAl， 硼原子强烈地偏聚在晶界上，当硼含量为1.37at%时，偏聚到晶界上的硼达到饱和，晶界的强化效果最好，更高的硼导致硼化物的共晶析出，产生较大开空间的缺陷，使晶界弱化。随着氢量在多晶Ni_3Al中的增加，它的行为存在两个明显的阶段，即氢对空位型缺陷的填充效应和氢致缺陷。被硼填充后的缺陷，对氢的捕获能力下降，偏聚在晶界上的硼能够抑制氢聚集在Ni_3Al合金的晶界上，适量的硼对晶界有明显的强化效果，能有效增加抵抗裂纹扩展的能力，增强多晶Ni_3Al合金的抗氢能力。 |
| Other Abstract | The recovery behaviour of deformed Ni-Cr-Co superalloys, the effect of boron on vacancy-like defects of Ni_3Al alloy, the interaction between hydrogen and defects in polycrystall Ni_3Al alloy have been studied by positron annihilation technique and transmission electron microscopy. Two recovery stages of annealing are found in deformed Ni-Cr-Co superalloy. The first recovery stage is due to vacancy moving, the second stage is attributed to dislocation motion and recrystallization. The beginning recrystallization temperature of Ni-Cr-Co superalloy is about 500 ℃. Under the same reduction, the less the Co Content in the alloy is, the more the defects are. In the recovery process, the dislocation in lower Co content alloy recover faster than of in higher Co content alloy. The apparent activation energy of recrystallization of the alloy increases with Co content. The openning space of the grain boundary is larger than that of the dislocation and vacancy in polycrystall Ni_3Al Alloy. When boron atoms are added to single crystal and polycrystall Ni_3Al alloy, some of them are solid solutioned in the crystal lattice of Ni_3Al in a manner of occupying interstitial sites, and the others are resided in vacancy like defects. The content of boron in the Ni_3Al alloy reaching 1.37at% may be a saturation point for filling to defects. Further increasing the content of boron can produce more defects. In polycrystall Ni_3Al alloy, boron atoms tend to segregate strongly to grain boundaries. When boron content reaching 1.37at%, the boundaries are filled by boron atoms, the strengthening effect by grain boundary is largest. If boron addition is too high, there are boride eutectie pricipitating in grains and at grain boundaries, the larger open-space defects appear, and the grain boundaries become weak. With the increasing of hydrogen in polycrystall Ni_3Al alloy with different boron content, its behaviour can be concluded to two obvious stages: the first stage is the effect of hydrogen atoms filling in the vacancy-like defects, the second stage is hydrogen producing defects. The ability to trap positrons of the defects which have been filled with boron atoms become feeble. Boron atoms segreting to grain boundaries can inhibit hydrogen atoms gathering to the grain boundaries. Suitable boron atoms obviously increase the cohesion of grain boundaries, resist the crack propagration and enhance the anti-hydrogen ability of polycrystall Ni_3Al alloy. |
| Pages | 74 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.imr.ac.cn/handle/321006/17526 |
| Collection | 中国科学院金属研究所 |
| Recommended Citation GB/T 7714 | 邓文. 镍基高温合金的正电子湮没研究[D]. 中国科学院金属研究所. 中国科学院金属研究所,1991. |
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