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The stereo morphology of ordinary dislocations in the γ\|phase in a Ti\|48Al alloy after compressed 2% at 800℃ was studied by developing an accurate stereo microscopy method. It was shown that the segments on one dislocation do not lie on the same plane. Some segments nearly lie on (111) while the others on (112),forming a helix. The dislocation helices might result from the cross slip of some segments on an initial screw dislocation from (111)plane to (112) plane. With the further slipping of the dislocation... The stereo morphology of ordinary dislocations in the γ\|phase in a Ti\|48Al alloy after compressed 2% at 800℃ was studied by developing an accurate stereo microscopy method. It was shown that the segments on one dislocation do not lie on the same plane. Some segments nearly lie on (111) while the others on (112),forming a helix. The dislocation helices might result from the cross slip of some segments on an initial screw dislocation from (111)plane to (112) plane. With the further slipping of the dislocation segments on (111) and (112),the line orientation nearby the nodes of adjacent segments will change,and the segments with larger edge components would deviate from (111) or (112) planes by climbing. 利用自行开发的精确立体显微术研究了 80 0℃压缩变形 2 %的双相TiAl基合金γ相中普通位错的空间形态。研究结果表明 ,同一位错往往并不处于同一晶面 ,其中一些位错段靠近 (111)晶面 ,另一些则靠近 (112 )晶面 ,构成三维螺旋状曲线。普通位错形成这种螺旋状曲线是交滑移的结果 ,即原先在 (111)密排面滑移的螺位错的部分位错段交滑移到 (112 )非密排面。随着处于不同晶面的位错段的进一步滑移 ,靠近位错段交界处的位错线方向将发生变化 ,具有较大刃型分量的部分可通过攀移而偏离 (111)或 (112 )晶面 To ascertain whether augmentation with calcium phosphat cement can enhance pedicle screw fixation in spine, 28 cadaveric lumbar vertebral bodies (L3 L5) were instrumented with pedicle screws. In 16 of these specimens, axial pull out strength and energy absorption were compared between the control screws and those augmented with α BSM TM cement. In the remaining 12 specimens, the screws were loaded in the superior inferior direction with increasing forces. The pull out strength of the augmented pedicles... To ascertain whether augmentation with calcium phosphat cement can enhance pedicle screw fixation in spine, 28 cadaveric lumbar vertebral bodies (L3 L5) were instrumented with pedicle screws. In 16 of these specimens, axial pull out strength and energy absorption were compared between the control screws and those augmented with α BSM TM cement. In the remaining 12 specimens, the screws were loaded in the superior inferior direction with increasing forces. The pull out strength of the augmented pedicles was increased by 66.8 % as compared with that on the control side. The energy absorption to failure and the energy 2mm were increased by 169.5 % by α BSM TM augmentation and by 60.6 % for the augmented specimens respectively as compared with those in the control group ( P <0.01). In cyclic load tests, augmented screws were found to withstand a greater number of cycles or greater loading before loosening. The data suggest that augmentation with this calcium phosphat cement can enhance the initial screw fixation both for pullout and cyclic loading. 为探讨添加新型陶瓷对改善椎弓根螺钉稳定性的影响 ,将椎弓根螺钉分别植入 2 8个 L3~ L5椎体两侧椎弓根 ,随机在一侧加 α- BSMTM。16个椎体做螺钉轴向拔出试验 ,测试最大轴向拔出力 (Fmax)和拔出过程中的能量吸收值E- Fmax和 E- 2 mm。另外 12个椎体做梯增负荷的螺钉周期抗屈试验。两组相比较发现 ,加入 α- BSMTM后 ,Fmax增加了6 6 .8% ,E- Fmax和 E- 2 mm分别增加了 16 9.5 %和 6 0 .6 % ,差别有统计学意义 (Wilcoxon's检验 ,P<0 .0 1)。周期抗屈试验中 ,添加α- BSMTM可使螺钉耐受更大的负荷或在同等负荷下仅产生较小的位移。结果表明 :在椎弓根螺钉植入时添加α- BSMTM能显著提高其初始的稳定性
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