纳米Ag颗粒增强复合钎料蠕变性能的研究

制备纳米Ag颗粒增强的Sn-Cu基复合钎料.研究不同温度载荷下复合钎料钎焊接头的蠕变断裂寿命,并与Sn-0.7Cu基体钎料钎焊接头进行对比.此外,确定纳米Ag颗粒增强的Sn-Cu基复合钎料钎焊接头在不同温度和应力水平下的应力指数和蠕变激活能,建立复合钎料钎焊接头的稳态蠕变本构方程.结果表明,在不同的温度和应力下,与Sn-0.7Cu钎料钎焊接头相比,纳米Ag颗粒增强的Sn-Cu基复合钎料钎焊接头的蠕变断裂寿命均有所提高,且具有更高的蠕变激活能,说明复合钎料钎焊接头具有更优的抗蠕变性能.     

Sn-9Zn无铅钎料合金的压蠕变行为研究

试验研究了Sn-9Zn合金钎料在温度为40～100℃和压力为9．3～18．6MPa范围内的压蠕变行为。结果表明：随温度和应力的升高，合金的压蠕变量增大，稳态蠕变速率的对数分别与应力对数和温度呈较好的线性关系，稳态蠕变速率符合半经验公式。在不同的温度下，应力指数n相近，平均值为5．74；不同的应力下，表观激活能Qa相差不大，平均值为51．95kJ／mol，材料结构常数为0．03，压蠕变变形是位错滑移和位错攀移共同作用的结果，控制稳态蠕变速率的主要因素为位错管道扩散过程控制下的位错攀移。     

Sn-8Zn-3Bi无铅钎料压蠕变行为的研究

试验研究了Sn-8Zn-3Bi无铅钎料在温度为55～100 ℃、压力为9.3～18.6 MPa范围内的压蠕变行为.结果表明,随温度和应力的升高,合金的压蠕变量增大,稳态蠕变速率的对数分别与应力的对数和温度呈线性关系.在试验温度下,应力指数n相近,平均值为3.82;在不同的应力下,表观激活能Qa相差不大,平均值为80.68 kJ/mol.材料结构常数A为6.83×104.压蠕变变形是位错滑移和位错攀移共同作用的结果.     

63Sn37Pb钎焊接头稳态蠕变本构方程的建立

采用高温蠕变测试装置，以简化的Dorn公式为基础．对63Sn37Pb微型单搭接钎焊接头蠕变应变进行了测试．确定了应力指数、蠕变激活能以及相关常数。建立了63Snd7Pb钎焊接头稳态蠕变本构方程，描述了稳态蠕变速率与应力和温度相关性。结果表明，钎焊接头应力指数和激活能均低于钎料本身的应力指数和激活能．说明钎料本身蠕变行为并不能完全代表钎焊接头的蠕变行为。     

Ti-600合金的高温蠕变行为

研究了Ti-600合金在550～650℃下的高温蠕变行为,实验应力为150～300 MPa.计算了合金在不同应力、不同温度下的稳态蠕变速率、应力指数及蠕变激活能,并在此基础上研究了其蠕变强化机制.蠕变应力为300 MPa时,Ti-600合金的蠕变激活能Q=490.1 kJ/mol;650 ℃,合金的蠕变应力指数n值在6.5～8.5之间变化,表明在实验温度范围内合金的蠕变变形以位错攀移为主,以位错的滑移为辅.     

应力对SnPb基复合钎料钎焊接头蠕变性能的影响

采用搭接面积为1mm^2的单搭接钎焊接头，研究了恒定温度下，应力对纳米颗粒增强的SnPb基复合钎料钎焊接头的蠕变寿命的影响。结果表明，纳米颗粒增强的SnPb基复合钎料的蠕变抗力优于传统SnPb钎料。同时钎焊接头的蠕变寿命随应力增加而降低，且应力对复合钎料钎焊接头蠕变寿命的影响较传统63Sn37Pb钎料明显。     

Mg-5.5Zn-2Gd-0.6Zr铸造镁合金的蠕变机制

在ZM-1(Mg-5Zn-0.6Zr)合金的基础上,适量增加Zn的含量并加入重稀土元素Gd,设计了Mg-5.5Zn-2Gd-0.6Zr实验合金。采用砂型铸造工艺制备实验合金试样,在不同温度和应力条件下对该实验合金和ZM-1合金的蠕变曲线进行了测试。结果表明:在相同条件下,Mg-5.5Zn-2Gd-0.6Zr实验合金的稳态蠕变速率较ZM-1合金的降低了一个数量级;当施加应力为40 MPa时,实验合金的蠕变激活能Q200-250℃=142.0 kJ/mol,接近镁的自扩散激活能,蠕变受位错攀移控制,而ZM-1合金在相同应力下蠕变激活能Q200-250℃=88.5 kJ/mol,接近镁的晶界扩散激活能,蠕变受晶界滑移控制。合金在200℃条件下的应力指数n=4.21,而ZM-1合金的应力指数n=2.21。因此,认为加入重稀土元素Gd后实验合金的蠕变机制发生改变,200℃时的蠕变机制为位错攀移机制。     

V-N微合金化钢的高温塑性变形行为研究

通过Gleeble-3800热模拟试验机对V-N微合金化钢进行了热模拟压缩试验,分析了V-N微合金化钢高温下塑性变形的变化规律,并通过分析应力一应变曲线,建立形变抗力模型和应变速率本构方程.结果表明,V-N微合金化钢在较低应变速率和较高温度下,流变应力随变形程度的不断增加而增加至某一峰值,然后逐渐下降至某一稳态值;应变速率、温度和峰值应力之间的关系可用幂指数关系来描述,在较低温度(900～950℃)下,应力指数约为7.1,变形激活能为118～185 kJ/mol,变形机制属于位错芯区扩散控制的幂律蠕变;在较高温度(1000～1150℃)下,应力指数约为6.6,变形激活能为125～285 kJ/mol,变形机制属于位错芯区控制的幂律蠕变.     

Sn-0．7Cu无铅钎料的压入蠕变行为研究

采用自制的蠕变装置研究Sn-0.7Cu合金钎料在温度为60～120 ℃,压力为30～50 MPa下的压入蠕变性能,并利用SEM和XRD对合金蠕变前后组织的变化进行分析.结果表明,随温度和应力的增加,合金的蠕变速率增大,稳态蠕变速率符合半经验公式,并得出了该合金的本构方程.通过对其蠕变后应力指数、蠕变激活能及显微组织变化的分析,压入蠕变变形机制主要由位错攀移引起.     

Mg-Al-RE-Ca合金的压缩蠕变行为研究

采用自制实验装置研究了铸态Mg-4Al-IRE-1.2Ca合金在125～175℃、88～112MPa范围内的压蠕变行为.结果表明:随温度和应力升高,合金的压蠕变量增大.稳态蠕变速率符合半经验公式.在不同的温度下,应力指数n相近,平均值为6.24;在不同的应力下,表观激活能Qa相差不大,平均值为37.51 kJ/mol,材料的结构常数为2.88x10-13,稳态蠕变速率由位错攀移控制.合金中沿晶界分布的Al2Ca相具有很高的热稳定性,能提高合金的抗蠕变性能.     

The influence of temperature on creep behavior of Cu particle enhanced SnPb based composite soldered joints

Creep property of solder alloys is one of the important factors to affect the reliability of soldered joints in SMT(surface mount technology). Particle-enhancement is a way to improve the properties of solder alloys and has caused much more attention than before. Temperatures applied to soldered joints are one of the primary factors of affecting creep properties of particle enhancement composite soldered joints. In this paper single shear lap creep specimens with a 1 mm2 cross-sectional area were fabricated using Cu particle enhancement 63Sn37Pb based composite soldered joints and 63Sn37Pb eutectic soldered joints to examine the influence of temperature on creep behavior of soldered joints. Results indicated that the creep resistance of soldered joints of Cu particle enhancement 63Sn37Pb based composite soldered joint was generally superior to that of the conventional 63Sn37Pb soldered joint. At the same time, creep rupture life of the composite soldered joint was declined with increasing temperature and drop faster than that of the conventional 63Sn37Pb eutectic soldered joint.     

Creep behavior on Ag particle reinforced SnCu based composite solder joints

1 Introduction The EU had issued the WEEE mandate that aimed to prohibit the use of SnPb solders by 2006. Under the pressure of legislation and trade competitions, large electronic manufacturers and research institutes studied substitutes for SnPb solders…     

Microstructural evolution and creep properties of Mg-4Sn alloys by addition of calcium up to 4 wt.%

The effects of addition of calcium up to 4 wt.% on the microstructure and creep properties of Mg-4Sn alloys were investigated by the impression creep test. Impression creep tests were performed in temperature range between 445 and 475 K under normalized stresses σ/G (where σ is the stress; G is the shear modulus) between 0.0225 and 0.035. Optical microscopy and scanning electron microscopy were used to study the microstructure of samples. It is observed that the addition of Ca more than 2 wt.% suppresses less stable MgSn₂ phase, and instead forms more thermally stable phases of Ca-Mg-Sn and Mg₂Ca at the grain boundaries which improve the creep resistance of Mg-4Sn alloys. According to the stress exponents (6.04<n<6.89) and activation energies (101.37 kJ/mol<Q<113.8 kJ/mol) which were obtained from the impression creep tests, it is concluded that the pipe diffusion climb controlled dislocation creep is the dominant creep mechanism.     

Investigation of primary and secondary creep deformation mechanism of TiAl

Creep deformation behaviors in lamellar TiAl alloys have been investigated. As in the case with metals, the normal primary creep stage was observed. As creep strain increased within the primary regime, dislocation density decreased, and creep activation energy increased from 300 kJ/mol, the activation energy of the self-diffusion of Ti in TiAl, to about 380 kJ/mol, that of steady state creep deformation. During primary creep deformation of lamellar TiAl, as the initial dislocation density decreased, the α₂ -phase was found to transform to a γ-phase, generating new dislocations which contributed to the creep deformation. In other words, this phase transformation is the source of the dislocation generation for continuous creep deformation. Therefore, we suggest that phase transformation is the rate controlling processes having an activation energy of about 400 kJ/mol, which is higher than that of self-diffusion. A small amount of prestrain was found to be responsible for the reduction of initial dislocation density. In addition, this prestrained specimen showed significantly reduced primary creep strain, and the creep activation energy in the primary stage was measured to be about 380 kJ/mol. These results clearly confirm the suggested creep deformation mechanism of lamellar TiAl alloys.     

AgInCd合金压缩蠕变性能研究

用RDL-50型拉伸蠕变试验机进行改装后的实验装置研究了铸态AgInCd合金在温度300~400℃及应力范围12~24 MPa内的压缩蠕变行为,分析了稳态速率与温度和应力的关系,计算了应力指数(n)和蠕变激活能(Q_a),并结合蠕变后样品在透射电子显微镜下的微观形貌及位错组态,探讨了合金的压缩蠕变机制。结果表明:随温度和应力水平的升高,合金的稳态蠕变速率增加。相比较指数关系,蠕变速率与应力之间更符合幂函数关系。300、350和400℃条件下,合金的蠕变应力指数n分别为3.31、4.09和5.77;12、18和24 MPa条件下,合金的蠕变激活能Q_a分别为68.1、103.7和131.6 kJ/mol。微观形貌以层错为主,孪生为300℃的主要蠕变机制,位错攀移生成位错墙为400℃的主要蠕变机制。     

Influence of stress on the creep behavior of Cu particle enhancement SnPb based composite solder joints

1. Introduction Mechanical fracture of solder joints is a major cause of failure and it decreases the reliability in electronic systems. With the increased functionality, miniaturization of electronic components, broad op-eration temperature ranges, and increased stress re-quirement, good mechanical properties are de-manded on solder joints. The eutectic tin-lead solder, which has a low melting point (183°C), plays an important role in SMT (surface mount technology). The working temperature…     

稀土Pr对低银Sn-0.3Ag-0.7Cu-0.5Ga钎料蠕变行为影响的研究

为进一步促进电子封装用低银无铅钎料的发展,本文采用纳米压痕法研究了新型含Pr低银Sn-0.3Ag-0.7Cu-0.5Ga (SAC-Ga)钎料显微组织与蠕变性能之间的关系。结果表明,SAC-Ga、SAC-Ga-0.06Pr、SAC-Ga-0.5Pr三种钎料的蠕变位移分别为1717 nm、1144 nm、1472 nm;稀土Pr可通过细化Cu₆Sn₅金属间化合物并促使其均匀分布从而明显提高SAC-Ga钎料的蠕变强度;与SAC-Ga-0.06Pr钎料相比,SAC-Ga-0.5Pr由于过量稀土Pr的表面氧化而导致其蠕变强度有所下降。此外,本文采用Dorn模型研究了含Pr的SAC-Ga钎料的室温蠕变行为并计算了对应的钎料蠕变应力指数n;阐明了Pr对SAC-Ga钎料蠕变强度的强化机理,即当位错遇到细小且均匀分布的Cu₆Sn₅ 金属间化合物时,位错移动只能采用绕过机制,从而提高了含Pr低银钎料的抗蠕变性能。