在1173—1323K温度范围内研究了Ni-20Cr合金蠕变行为与位错亚结构的关系.在蠕变初期出现蠕变速率几乎不变的亚稳态阶段.电镜观察表明,亚稳态蠕变和未形成亚晶的均匀位错结构相对应.亚稳态到稳态的蠕变速率连续降低的过渡阶段是蠕变中形成的亚晶界逐渐取代晶界起位错攀移相消位置的结果. 提出了控制稳态蠕变速率的亚结构参数是亚晶界位错网目尺寸,蠕变速率可用ε=αρtbV_c/h表示.根据位错在晶界或亚晶界上攀移相消控制的蠕变机制讨论了固溶碳和晶界碳化物对蠕变行为的影响.
The relationship between creep behavior and dislocation substructurein Ni-20Cr alloys has been studied over the temperature range of 1173-1323K. A stage of substeady-state creep was observed in which creep rate ε_t is al-most constant in the primary stage of creep. TEM observation confirmed that thesubsteady-state creep corresponds to relatively homogeneous dislocation structurewhile the steady-state creep corresponds to subgrain structure. The creep rate reducecontineously from ε_t to ε_m, which has been attributed to the gradual substitutionof subboundaries for grain boundaries as dislocation climb site. The substructural parameter, subboundary misorientation, θ, or subboundarymesh size, h, has been related to the steady-state creep rate in recovery creep, whichcan be discribed as ε=αρ_t bV_c/h. A mechanism of recovery creep involving dis-location annihilation at subboundaries or grain boundaries was proposed and theeffect of solute carbon and grain boundary carbides on creep behavior has beendiscussed using above michanism.
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