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首页> 外文期刊>Philosophical Magazine Letters >On the dislocation pole mechanism for twinning in TiAl crystals
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On the dislocation pole mechanism for twinning in TiAl crystals

机译:TiAl晶体孪晶的位错极机理

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摘要

A dislocation model is proposed for twin formation in the L1 structure, under a compressive applied stress along the c axis, on the basis of the original pole mechanism for twinning in the fcc structure. Dissociation of a jog on an ordinary [110]/2 dislocation into a Shockley and a Frank partial in TiAl is energetically favourable according to anisotropic elasticity theory. While a pileup of [101] superdislocations assists a Shockley loop to spiral around two sessile nodes, the Frank partial expands under mechanical and chemical stresses and mitigates the high repulsive interaction between two Shockley partials. Available data on the apparent critical resolved shear stress for twinning in Ti-56 at.% Al single crystals are explained in terms of reasonable values of a local stress concentration factor and a vacancy supersaturation at elevated temperatures.
机译:在fcc结构中孪生的原始极点机制的基础上,在沿c轴施加压缩应力的情况下,提出了L1结构中孪晶形成的位错模型。根据各向异性弹性理论,在普通的[[110] / 2位错上,将慢进点分解为TiAl中的Shockley和Frank部分在能量上是有利的。虽然[101]超位错的堆积有助于Shockley环在两个无柄节上成螺旋形,但Frank部分在机械和化学应力作用下膨胀并减轻了两个Shockley部分之间的高排斥性相互作用。关于Ti-56 at。%Al单晶中孪晶的表观临界解析剪切应力的可用数据,是根据局部应力集中系数和高温下的空位过饱和的合理值进行解释的。

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