轧制方向对喷射沉积含Nd镁合金第二相及织构影响

Second Phase and Texture of Spray-Deposited Magnesium Alloy Containing Nd with Different Rolling Directions

采用喷射沉积技术制备Mg-9Al-3Zn-1Mn-6Ca-2Nd合金沉积坯,对其进行挤压预变形和轧制变形（T=350℃,ε=25%和35%）,利用扫描电子显微镜（SEM）和X射线衍射仪（XRD）研究轧制变形对镁合金组织及织构的影响。结果表明：尺寸不对称的镁合金板材在350℃分别经过90°和0°方向轧制后,镁合金除了有Mg基体、（Ca,Nd）Al2（块状和颗粒状C15相）相外,在0°方向轧制后还存在Mg0.97Zn0.03相。随道次压下率（ε=25%和35%）增大,分别沿90°和0°方向轧制后颗粒状C15粒子会明显增多,但在90°方向轧制后块状、颗粒状C15粒子均发生＂团聚现象＂。0°方向轧制过程中细小弥散的C15粒子阻碍位错运动形成位错缠结区有利于Zn元素扩散,是0°方向轧制Mg0.97Zn0.03相保留的重要原因;随道次压下率增大,在0°方向变形后尺寸不对称的镁合金板材形成较弱（0002）基面织构的同时且柱面织构{1120}〈1010〉和锥面织构{1012}强度也逐渐增强,即实现了镁合金形变织构的随机化,轧制过程中基面滑移Schmid因子变化是影响尺寸不对称镁合金形变织构随机化的主要原因。

The billets of Mg-9 Al-3 Zn-1 Mn-6 Ca-2 Nd alloy produced by spraying deposition method(the Osprey process） were studied by scanning electron microscopy(SEM） and X-ray diffractometer(XRD） in order to analyze the effect of rolling(T = 350 ℃ and pass reduction ε = 25% and 35%） on microstructure and texture of pre-extruded magnesium alloy. The results showed that the size-asymmetry Mg alloy had not only Mg matrix and(Ca,Nd） Al2(block-like and granule-like C15 phase） phase distributing along the rolling direction of 90° and 0° at 350 ℃,but also Mg0. 97 Zn0. 03 phase after rolling deformation in the rolling direction of 0°. The granule-like C15 particles was prominently increased respectively after rolling along the rolling direction of 90° and 0° with the increase of pass reduction(ε = 25% and 35%）. And both block-like C15 particles and granule-like C15 particles had agglomeration phenomenon after rolling deformation in the rolling direction of 90°. Fine dispersed C15 particles impeding dislocation movement and then forming dislocation tangles promoting the diffusion of Zn,which was important for retaining Mg0. 97 Zn0. 03 phase along the rolling direction of 0°. The size-asymmetry Mg alloy formed weak basal texture(0002） rolled along the rolling direction of 90° and 0° at 350 ℃,and the texture pole density levels of prismatic texture { 1120 } 1010 and pyramidal texture { 1012 } increased gradually after rolling deformation in the rolling direction of 0° with the increase of pass reduction(ε = 25% and 35%）,namely,texture randomization was achieved in Mg alloy. The change of Schmid factor of the basal slip system was the key to affecting texture randomization of the sizeasymmetry Mg alloy.