Directional recrystallisation in Inconel MA 6000 nickel base oxide dispersion strengthened superalloy
Directional recrystallisation in Inconel MA 6000 nickel base oxide dispersion strengthened superalloy
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DOI：
10.1179/mst.1990.6.12.1236
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发表时间：
1990-12
影响因子：
1.8
通讯作者：
M. M. Baloch-M.;H. Bhadeshia
中科院分区：
文献类型：
--
作者：
M. M. Baloch-M.;H. Bhadeshia
研究了氧化物弥散强化镍基高温合金中导致高度各向异性“新”晶长大的定向再结晶过程，以阐明再结晶的机理和控制组织演变的重要工艺参数。结果表明，经挤压和热变形后，合金由超细等轴晶组织组成，具有材料动态初生再结晶的特征。因此，当热轧样品在移动的温度梯度(区域退火区)中退火时，随后的定向再结晶实际上是二次再结晶现象。通过比较晶界迁移率和区域退火率，从理论上预测和实验观察到，当界面速度小于区域退火区速度时，定向再结晶将让位于等轴再结晶。当温度和时间的影响被合并为一个参数，即热处理的动力学强度时，各向异性区退火过程中涉及的变量似乎是合理的。发现只有当超过动强度的临界值时，才会发生定向再结晶，而与区退火过程中的峰值温度或横移速度无关。MST/1268
The directional recrystallisation process which leads to the growth of highly anisotropic ‘new’ grains in an oxide dispersion strengthened nickel base superalloy is investigated to elucidate the mechanism of recrystallisation and the process variables important in controlling microstructural evolution. It is found that after extrusion and hot deformation, the alloy consists of an ultra fine equiaxed grain microstructure characteristic of a material which has undergone dynamic primary recrystallisation. Thus, the directional recrystallisation which follows when the hot rolled sample is annealed in a moving temperature gradient (zone annealed) is really a secondary recrystallisation phenomenon. By comparing grain boundary mobility with the rate of zone annealing, it was theoretically predicted and experimentally observed that directional recrystallisation should give way to equiaxial recrystallisation when the interface velocity is less than the speed of zone annealing. The variables involved in the anisothermal zone annealing process appear to rationalise when the effects of temperature and time are consolidated into a single parameter, the kinetic strength of the heat treatment. Directional recrystallisation is found to occur only when a critical value of the kinetic strength is exceeded, irrespective of the peak temperature or traverse speed during zone annealing. MST/1268