喷射成形A356铝合金组织及力学性能的研究

采用自行开发的控制往复喷射成形专利技术,以产业化规模制备了铝合金锭坯,研究了对传统铸造A356铝合金的组织及其力学性能的影响.结果表明:喷射成形态合金组织均匀,致密度达到95.8%;挤压态合金中均匀分布大量细小Si颗粒;固溶温度为540℃,时效温度为160℃,时效10 h时硬度达到峰值,继续延长时效时间对硬度值影响甚微;经过固溶时效处理的A356铝合金常温抗拉强度σb=337 MPa,屈服强度σ0.2=281 MPa,伸长率δ5=18.3%,分别提高21.2%,35.7%,205%.     

Effect of strontium on columnar growth of dendritic α phase in near-eutectic Al-11.6%Si alloys

For Al-11.6 % Si alloy, the influence of the addition of Sr on the morphology of the dendrite α phase was investigated, and the characteristic parameters of the dendrite α phase, the primary dendrite spacing and the secondary dendrite arm spacing, were also measured. The addition of strontium promotes the columnar dendrite growth and leads to a decrease of both the primary dendrite spacing and secondary dendrite arm spacing with the increase of the content of strontium in the modified near-eutectic Al-Si alloys. It is thought that the addition of Sr leads to a reduction of the solid-liquid interfacial energy of the dendrite α phase, consequently resulting in a decrease of the growth undercooling of dendrite tips. And hence, the nucleation of the equiaxed grains in the liquid in front of the columnar dendrite tips is restrained, thus the addition of strontium in Al-Si alloys promotes the growth of the columnar dendrites. The reduction of the solid-liquid interfacial energy also leads to the decreases in the primary dendrite spacing and the secondary dendrite arm spacing.     

用稀土添加剂改善中硅铝合金性能的研究

用一种稀土添加剂(自制)向ZAlSi7MglA铸造铝合金中加入稀土元素，以改善合金的性能。结果表明：该法使稀土元素的加入操作变得简单易行，烧损小，合金性能改善效果明显，在一定RE浓度范围内随着合金中RE含量增加合金的Rm和A同步增长。通过试验得到了最佳效果的稀土加入量。     

涡流法检测铝硅合金显微组织的误差分析

当采用涡流法检测铝硅合金活塞显微组织级别时，合金的含硅量、变质剂的加入量以及温度变化都将影响分级结果的准确性。分析了由以上因素引起的显微组织的分级误差，确定了含硅量不同时的修正因子，变质剂的加入量以及温度变化时的校核方式，并采用数理统计方法分析了测试的可靠性，最后得出该涡流检测的分级准确率可迭99％。     

二元合金等轴枝晶生长相场模拟

在传统纯物质相场模型的基础上，对其中的体系自由能进行重新构造，得到一个紧密联系相图且综合考虑了传热、溶质扩散、界面能各向异性和界面动力学各向异性等适用于二元合金枝晶生长的新相场模型，并利用该模型结合一种能显著提高计算效率的“临界面点相场大梯度计算域控制法”，对AJ-7Si合金在初始过冷度分别为35K和50K的过冷熔体中等轴枝晶生长进行了模拟，得到许多与试验观察相符合的结果；同时在枝晶生长过程中跟踪枝晶主轴尖端，获得其尖端半径和尖端速率，发现随着凝固时间的增加，逐渐收敛，直到枝晶达到稳定生长，而且通过简化KGT模型计算的枝晶尖端的生长速率与模拟值相近。另外，就过冷度对等轴枝晶生长的影响进行了分析。     

Exploring the reactivity and nanoscale morphology of de-alloyed layers

De-alloying of a 70Cu-30Pt alloy has been studied with a view to testing the thermodynamic prediction that a novel kind of underpotential or sub-potential electrodeposition may be possible in such highly curved nanoporous solids. After de-alloying in H₂SO₄ solution containing CuSO₄, successive cathodic processes of PtO monolayer reduction, UPD of Cu, and a Cu plating process were identified, all occurring at potentials above the Cu equilibrium potential. The maximum amount of charge in the third plating process was determined to be about three monolayers, averaged over the whole porous surface. This seems to rule out the possibility that this process is some kind of second UPD layer or other non-bulk form of Cu plating. A probable explanation is that small amounts of bulk Cu are plating into regions of high negative curvature within the de-alloyed material. However X-ray diffraction did not show any evidence of bulk Cu.     

实型铸造在轿车玻璃检具制造中的应用

介绍了基于数控加工泡沫模样原型与实型铸造技术相结合的轿车玻璃检具的快速制造。结果表明，采用数控铣床进行检具泡沫模样的加工，加快了泡沫模样的制作，保证工作面加工余量均匀，从而减少了铸件加工量；实型铸造不需起模，保证了检具毛坯的完整性，满足了客户要求。     

喷射沉积Al-17Si-5Fe-2Mn-2Ni-3.5Cu-1Mg-1V合金的组织及性能

采用喷射沉积快速凝固技术制备了Al-17Si-5Fe-2Mn-2Ni-3.5Cu-1Mg-1V合金,利用金相、X射线衍射和SEM等测试方法分析了合金的组织特征、热稳定性及力学性能。结果表明：喷射沉积合金的组织由大量弥散分布的粒状相、少量块状相和共晶基体组成。挤压态合金经300℃不同时间加热后,初晶Si相没有明显的粗化,热稳定性良好;合金经热挤压后,室温极限拉强度达232.2 MPa,经T6热处理后极限抗拉强度提高了17%,达271.3 MPa。     

淬火介质对7055铝合金晶界析出行为的影响

采用透射电镜研究了淬火介质对7055铝合金晶界析出相及无沉淀析出带的影响。结果表明，空气淬火时，合金冷却过程在晶界上析出η平衡相。合金经室温水淬及沸水淬火合金时效后，晶界析出相尺寸差别小，呈链状连续分布；晶界无沉淀，析出带较窄，平均宽度分别约为33nm和43nm。空气淬火合金时效后晶界析出相尺寸差别较大，呈不连续分布；晶界无沉淀，析出带很宽，约102nm。对其原因进行了分析和讨论。     

Mg-6Al-1Nd-1.5Gd合金的高温蠕变机制

采用高温蠕变装置,研究了Mg-6Al-1Nd-1.5Gd合金在150、175、200℃以及50、70、90 MPa条件下的高温压缩蠕变行为,分析合金在高温蠕变过程中的蠕变机制。结果表明,Mg-6Al-1Nd-1.5Gd合金的平均应力指数及蠕变激活能分别为4.64和73.87kJ/mol,其主要蠕变机制是由位错攀移和晶界扩散共同作用,合金的蠕变本构方程为:ε=1.877×10-8σ4.641exp[-73 865/(RT)];合金在高温蠕变过程中,微观组织中的位错密度逐渐增大,出现位错缠结及位错堆积,合金蠕变后的晶粒变得粗大,金属间化合物Al3Nd和Al3Gd在晶界上出现偏聚。