Estimation of Dislocation Concentration in Plastically Deformed Al-Li Based Alloy by Positron Annihilation
Estimation of Dislocation Concentration in Plastically Deformed Al-Li Based Alloy by Positron Annihilation
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DOI：
10.1143/jjap.36.6530
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发表时间：
1997-10
影响因子：
1.5
通讯作者：
M. Abdel-Rahman
中科院分区：
文献类型：
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作者：
M. Abdel-Rahman
本文对八种不同的铝锂基合金室温塑性变形试样进行了正电子湮没平均寿命τ的测量。这个测量清楚地表明正电子被位错俘获。当变形量大于15%时，正电子寿命τ出现饱和。拟合寿命从退火样品的（183 ±2 ps）到位错饱和值的（205 ±2 ps）。采用陷阱模型，得到比陷阱速率μ= 3.83×10-8 cm ~ 3·s ~（-1），陷阱截面σ= 3.58×10-15 cm ~ 2，略低于塑性变形Al单晶。获得的Δτ值为22 ps，Δ τ是塑性变形的Al-Li基合金样品中位错处捕获的正电子寿命相对于退火样品中湮灭的增加。这是约40%的寿命增加的情况下，被困在位错的塑性变形铝单晶的正电子。估算了不同减薄量下的位错密度。
Measurements of positron annihilation mean lifetime τ have been performed on eight different specimens of Al–Li based alloy plastically deformed at room temperature up to 40% thickness reduction. This measurement shows clearly positron trapping by dislocations. The positron lifetime τ exhibits a saturation for deformations larger than (15%) thickness reduction. The fitted lifetime varies from (183 ±2 ps) for annealed sample to (205 ±2 ps) for the dislocation saturated value. Using a trapping model, the data yield the values of µ= 3.83×10-8 cm3 s-1 for the specific trapping rate and σ= 3.58×10-15 cm2 for the trapping cross section, some what lower than those for plastically deformed Al single crystals. The value obtained for Δτ, the increase in lifetime of positrons trapped at dislocations in plastically deformed Al–Li based alloy sample over annihilation in the annealed sample, is 22 ps. This is about 40% of the lifetime increase for the case of positrons trapped at dislocations in plastically deformed Al single crystals. Dislocation densities at different thickness reduction have been estimated.