FeNbB合金有效各向异性与温度关系

研究了Fe83Nb6B11合金有效各向异性〈k〉与温度t的关系,结果表明:淬态Fe83Nb6B11非晶有效各向异性随温度的升高呈线性减小,热处理后的非晶和纳米双相合金的有效各向异性〈k〉随温度的升高变化不同,热处理温度低于530℃时样品的有效各向异性〈k〉值在非晶居里温度减小,而热处理温度为580℃时样品的有效各向异性〈k〉值在非晶居里温度变化很小·     

Zr对Sr变质近共晶Al-Si铸造合金组织的影响

Sr作为变质剂加入到Al-Si合金中能导致共晶硅的形态从粗在的片状（或针状）转变为细小的纤维状,但同时也促进长柱状枝晶的形成。为了抑制长柱状枝晶的形成,本研究采用金相显微镜和扫描电镜分析Zr对Sr变质近共晶Al-Si铸造合金组织的影响。结果表明,随着Zr加入量的增加,枝晶α（Al）有等轴化趋势,长柱状枝晶的主干长度缩短,且对共晶硅的形态、尺寸没有明显影响,当Zr加入量为0.5～0.6%时,枝晶α完全等轴化。这是由于熔体中形成了ZrAl3颗粒,在合金凝固过程中,起到了异质生核作用。     

蛇形通道制备半固态A380铝合金浆料组织的演变

采用石墨质蛇形通道制备半固态A380铝合金浆料,并研究浆料制备过程中浆料组织的演变. 结果显示,合金熔体在蛇形通道内发生一次凝固,在其通道内壁的激冷和异质形核作用下形成大量的初生自由晶,半固态浆料的剩余液相在收集坩埚内发生二次凝固形成二次非枝晶. 初生晶粒的游离模型表明一部分初生自由晶直接生长为球晶,其他部分则成长为枝晶,枝晶在"自搅拌"的作用下发生缩颈和熔断,通过"自旋转"在蛇形通道内得到初步球化和熟化. 二次凝固形成的二次非枝晶在收集坩埚内得到初步球化和熟化,同时初生晶粒在收集坩埚内得到进一步球化、熟化和均匀分布.     

Effect of Sr on microstructure and aging behavior of Mg-14Li alloys

The as-cast and as-extruded Mg-14 wt％Li-xSr (x=0.14,0.19,0.39 wt％) alloys were,respectively,prepared through a simple alloying process and hot extrusion.The effects of Sr addition on microstructure and...     

反复熔铸对镍铬烤瓷合金离子析出影响的研究

根据ISO10271标准,将镍铬烤瓷合金在真空加氩气保护的铸造条件下,按口腔铸造要求分别经过1～5次熔铸制成方形试样,并在空气中960℃加热10min.试样抛光后浸泡于pH=2.35的0.1mol·L(-1)氯化钠溶液中,37℃密封保存7和70d后采用电感耦合等离子体原子发射光谱仪检测溶液中析出的离子,同时测量试样重量...     

Electronic origin of the anomalous solid solution hardening of Y and Gd in Mg: A first-principles study

Y and Gd demonstrate anomalous solid solution hardening efficiency,which cannot be understood using the elastic impuritydislocation interaction theory.We performed first-principles calculations to investigate the effect of different alloying elements such as Al,Zn,Y,and Gd on the chemical bonding of Mg solid solutions.The present calculations clearly show that the anomalous solid solution hardening of Y and Gd in Mg may be understood based on the increased bonding strength of both Mg-Y (Gd) and Mg-Mg.     

AZ71-Gd镁合金压铸件微弧氧化处理工艺研究

采用硅酸盐体系对AZ71-Gd镁合金压铸件进行了微弧氧化处理,研究了工艺参数和溶液成分对微弧氧化膜性能的影响,确定了硅酸盐体系中进行微弧氧化处理的最佳工艺方案为：微弧氧化电流1．5A／dm2,氧化时间15min,电解液温度35℃,硅酸钠12g/L,氢氧化钠2g/L,氟化钾4g/L,有机醇WOH6mL／L。     

水化学和腐蚀温度对锆合金氧化膜中压应力的影响

在不同水化学条件下,对Zr-4和N18管状样品进行腐蚀实验,然后用氧化膜卷曲法测量腐蚀样品氧化膜中的压应力,研究腐蚀温度、水化学对氧化膜中压应力随厚度变化的影响规律.实验结果表明,Zr-4和N18样品氧化膜中的压应力均按360℃去离子水>400℃过热蒸汽>360℃L iOH水溶液的顺序依次减小.在360℃L iOH水溶液中腐蚀时,氧化膜中的压应力最低,这与L i+和OH-会渗入氧化膜,降低氧化锆表面自由能,从而加速氧化膜中空位的扩散凝聚、孔隙的形成和微裂纹发展的过程有关.高温使空位的扩散加快,促进了氧化膜中压应力的弛豫过程.     

Toward the development of Mg alloys with simultaneously improved strength and ductility by refining grain size via the deformation process

Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously.Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility.In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced.Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence.This review can be used as a reference for further development of high-performance fine-grained Mg alloys.