Sr对Sb变质Mg-5Sn-1.5Al-1Zn-1Si合金组织的影响

用重力铸造法制备Sb及Sr＋Sb联合变质Mg-5Sn-1.5Al-1Zn-1Si合金,再进行不同的固溶处理,研究Sr对Sb变质Mg-5Sn-1.5Al-1Zn-1Si合金组织的影响。结果表明：Sb和Sr＋Sb联合变质均可以使初生Mg2Si和Mg2（Si,Sn）颗粒发生不同程度的球化,而Sr＋Sb联合变质比Sb单变质具有更好的细化和球化效果;Sr＋Sb联合变质后,共晶Mg2Si和Mg2（Si,Sn）相由汉字状变为细小近似球形或多边形颗粒状;Sb变质Mg-5Sn-1.5Al-1Zn-1Si合金在较低固溶温度和较短保温时间下即可使大部分Mg17Al12相和部分Mg2Sn相固溶到基体中,而Sr＋Sb联合变质合金组织中,Mg17Al12和Mg2Sn依然清晰可见,未完全溶解的Mg17Al12相发生球化,均匀的分散在基体中;Sr＋Sb联合变质Mg-5Sn-1.5Al-1Zn-1Si合金固溶温度要比Sb单变质时略高一些,但对固溶时间的影响并不明显。

Microstructures and tensile properties of as-cast Mg-5Sn-1Si magnesium alloy modified with trace elements of Y,Bi,Sb and Sr

The microstructures and mechanical properties of as-cast Mg-5 Sn-1 Si magnesium alloy modified with trace elements Y,Bi,Sb and Sr were investigated and compared.Results show that the microstructure of the as-cast Mg-5 Sn-1 Si alloy consists ofα-Mg,Mg_(2) Si,Mg_(2) Sn and Mg_(2)(Si_xSn_(1-x))phases.After adding 0.8 wt.%Y,0.3 wt.%Bi,0.9 wt.%Sb and 0.9 wt.%Sr,respectively into the Mg-5 Sn-1 Si magnesium alloy,Mg_(24)Y_(5),Mg_(3) Bi_(2),Mg_(3) Sb_(2) and Mg_(2) Sr phases are precipitated accordingly.Trace elements can refineα-Mg grain and Chinese scriptshaped Mg_(2) Si phase.Refinement efficiency of different trace elements onα-Mg grain and Mg_(2) Si phase is varied.Sr element has the best refinement effect,followed by Sb and Bi,while Y has the least refinement effect.Mg-5 Sn-1 Si-0.9 Sr alloy has higher tensile properties than the other three modified alloys.The refinement mechanism of Y,Bi and Sr elements on Mg-5 Sn-1 Si magnesium alloy can be explained by the growth restriction factors and the solute undercooling.For Mg-5 Sn-1 Si-0.9 Sb alloy,the heterogeneous nuclei of Mg_(3) Sb_(2) phase is the main reason for the refinement of grains and second phases.

Ag和Cu元素对Ni Au/Sn-5Sb/Au Ni焊点体钎料微观组织和蠕变性能的影响

通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)等仪器研究了Ni Au/Sn-5Sb/A u N i和N i A u/S n-5S b-0.7A g-0.5C u/A u N i焊点体钎料的微观组织,利用纳米压痕法研究了两种焊点体钎料在25~125℃的蠕变性能。结果表明:室温下,Ni Au/Sn-5Sb/Au Ni焊点体钎料中存在β-Sn和Sn Sb两相。在添加了Ag和Cu元素之后,Ni Au/Sn-5Sb-0.7Ag-0.5Cu/Au Ni焊点体钎料中除上述两相外,新生成了圆形颗粒状的Ag;Sn和短棒状的Cu;Sn;相。在相同的温度下,Ni Au/Sn-5Sb/Au Ni焊点体钎料的稳态蠕变速率、压痕深度和压痕面积均大于Ni Au/Sn-5Sb-0.7Ag-0.5Cu/Au Ni焊点。Ni Au/Sn-5Sb/Au Ni和Ni Au/Sn-5Sb-0.7Ag-0.5Cu/Au Ni焊点体钎料在25~125℃的平均蠕变应力指数分别为7.22和8.49,后者的蠕变应力指数相比前者提高了约17.6%。Ag和Cu元素的添加使Ni Au/Sn-5Sb/Au Ni焊点体钎料的抗蠕变性能出现较大程度的提升。

Effect of elements Ni and Co on morphology and type of IMC at Sn-3Ag-0.5Cu solder joint interface

The intermetallic compound (IMC) is hard and brittle,and its forming and growth at soldering joint interface is an important issue in joint reliability.The data obtained by digital optical electronic microscope indicate that the addition of element Co changes the IMC morphology from ball-like and bar-like to distinct and sharp in crest lines and edges.The addition of elements Ni and Co in Sn-3Ag-0.5Cu solder promotes the nucleation and makes the IMC size finer.The electron probe microanalysis (EPMA) determines the chemical compositions and confirms that the IMC is changed into the (Cu,Co,Ni)6Sn5+(Cu,Co,Ni)3Sn4 mixed type from the type of Cu6Sn5 with the elements Ni and Co in the solder.

Wetting Behaviors and Interfacial Reaction between Sn-10Sb-5Cu High Temperature Lead-free Solder and Cu Substrate

Sn-10Sb-5Cu lead-free solder was fabricated for high temperature application in electronic package. Wetting behaviors and interfacial reaction between such a high temperature lead-free solder and Cu substrate were investigated and compared with those of 95Pb-Sn solder. The results showed that the wetting properties of Sn-10Sb-SCu solder are superior to those of 95Pb-Sn solder in maximum wetting force, wetting time and wetting angle in the temperature range of 340-400℃. However, the surface of the Sn-10Sb-5Cu solder sample after wetting balance tests was rougher than that of 95Pb-Sn solder at the temperature lower than 360℃. In static liquid-state interracial reaction, the types and thickness of the intermetallic compounds （IMCs） of both solders were different from each other. The wetting kinetics in the Sn-10Sb-5Cu/Cu system was more rapid than that in 95Pb-Sn/Cu system, and the higher formation rate of IMCs in the former system was considered as the reason.

Crack Initiation and Propagation Evaluation for Sn–5Sb Solder Under Low-Cycle Fatigue

In this study, a crack initiation and propagation behavior of Sn-5Sb lead-free solder under low-cycle fatigue is discussed. Cyclic push-pull loading tests with a single-hole specimen have been conducted at 313 K to investigate the crack initiation and propagation behavior of Sn-SSb solder which has a higher melting point temperature than that of Sn- Ag-Cu solders. A fatigue life ratio correlates with the crack length within a small scatter. Crack initiates at the early stage, and almost all the life period is crack propagation process independent of strain range and strain rate. The crack propa- gation rate depends on the strain range and the strain rate. The adaptation of J-integral value for Sn-5Sb solder is also discussed. J-integral value is a suitable parameter for crack propagation rate evaluation.

铜铝异种金属钎焊工艺研究

由于Sn基钎料对硬铝的润湿性差及焊后服役过程钎焊接头耐腐蚀性降低的问题,因此制备高可靠性的大面积、高致密度的铜铝异种金属的钎焊接头是非常困难的。本文研究了铜与硬铝之间的钎焊连接工艺,提出了在硬铝表面化学镀Ni-P的方法,并且采用炉中钎焊来保证钎焊温度的均匀。试验结果表明:采用这一工艺方法可以很好地实现铜与硬铝之间的钎焊连接,所获得的钎缝没有明显的钎焊缺陷;在Ni-P/Sn-5Sb钎料界面形成(Ni,Cu)3Sn4相,而在Cu/Sn-5Sb钎料界面形成扇贝状的Cu6Sn5相。

Mg-5Sn-1.5Al-1Zn-1Si合金的高温变形机制

以Mg-5Sn-1．5A1-1Zn．1si合金为研究对象，分析了复合强化、sb元素及动态再结晶对合金高温变形机制的影响。结果表明：往复挤压镁合金经过复合强化与热处理后，晶界面积减少，晶界滑移得到有效控制，合金呈现优良的高温性能。对于Mg-5Sn-1．5A1-1Zn-1Si-xSb合金，Sb元素具有活性作用，能够改善其高温强度，200℃以上效果更为显著，这主要与Mg3Sb2的熔点高、热稳定性好有关。合金经过动态再结晶以后，晶粒变大，对高温变形更加有利，同时温度升高，对动态再结晶具有促进作用，加速塑性变形。