车削加工对铍组织与性能的损伤

报道了不同车加工工艺对铍表层的损伤以及机加工损伤对铍力学性能的影响，建立了消除机加工损伤的方法，随车加工吃刀深度和走刀量的增加，铍材表面损伤层在0.1～0.5mm范围内增加，机加损伤主要表现形式为形成表面孪晶，表层晶粒越粗大，孪晶密度越高，由于样品加工时采用了较小的吃刀深度和走刀量，在金相显微镜下未发现表面裂纹，机加工损伤使铍的抗拉强度和延伸率均有较大降低。化学蚀刻是消除机加工损伤的较好方法，750℃退火能部分消除机加工损伤，消除机加工损伤后，铍的力学性能又可得到恢复。     

Y含量对Mg-Zn-Y合金显微组织及力学性能的影响

采用金相显微镜、扫描电子显微镜、X-射线衍射仪以及电子万能实验机等设备,研究了Y对Mg-2Zn-xY（X=0、0．5、1、3,质量分数／％）舍金的显微组织及力学性能的影响。结果表明：随着Y含量的增加,合金二次相由Ⅰ相＋W相转变为W相＋H相。舍金力学性能随Y加入量的增加而提高,当加入量为1％时,合金的力学性能达到最佳：抗拉强度达到207MPa,伸长率达到16．9％;而加入量为3％时,综合力学性能又有所下降。     

Effects of Indium Content on Microstructural,Mechanical Properties and Melting Temperature of SAC305 Solder Alloys

The present study investigated the effects of indium (In) addition on the microstructure, mechanical properties, and melting temperature of SAC305 solder alloys. The indium formed IMC phases of Ag₃(Sn,In) and Cu₆(Sn,In)₅ in the Sn-rich matrix that increased the ultimate tensile strength (UTS) and the hardness while the ductility (% EL) decreased for all In containing solder alloys. The UTS and hardness values increased from 29.21 to 33.84 MPa and from 13.91 to 17.33 HV. Principally, the In-containing solder alloys had higher UTS and hardness than the In-free solder alloy due to the strengthening effect of solid solution and secondary phase dispersion. The eutectic melting point decreased from 223.0°C for the SAC305 solder alloy to 219.5°C for the SAC305 alloy with 2.0 wt% In. The addition of In had little effect on the solidus temperatures. In contrast, the liquidus temperature decreased with increasing In content. The optimum concentration of 2.0 wt % In improved the microstructure, UTS, hardness, and eutectic temperature of the SAC305 solder alloys.     

硅对易切削Bi黄铜组织及性能影响的研究

用PHILIPS-XL30型扫描电子显微镜（SEM）观察了不同硅含量对易切削铋黄铜组织的影响,采用HY-1080型电子拉伸试验机测试各试样的力学性能,使用C6136卧式普通机床检测合金切削性能.结果表明：硅的加入使铋黄铜中的β相比例增加,α相比例减少;铋黄铜的伸长率、断面收缩率随着硅含量的增加而下降,而材料的抗拉强度随着硅含量的增加而增加;铋黄铜的切削性能随着硅含量的增加而增加.     

Mn含量对Fe-Mn合金组织及力学性能的影响

利用扫描电镜、透射电镜、背散射电镜及拉伸和冲击试验研究了锰对含锰量为3%~12%的Fe-Mn合金组织和力学性能的影响。结果表明,当锰含量介于3%~9%时,随着锰含量的上升,高温相变产物(多边形铁素体和准多边形铁素体)受到抑制,合金的屈服强度和抗拉强度逐渐增加而均匀延伸率和总延伸率逐渐下降;当锰含量增加至12%时,合金中残留的少量亚稳ε马氏体和奥氏体在形变初期发生相变,产生的相变塑性使合金呈现出屈服强度下降的假象,但合金的抗拉强度、均匀延伸率和总延伸率均上升。由于晶界锰原子浓度的增加会减弱界面的结合力,故合金的冲击韧性随锰含量的增加而显著下降。为使Fe-Mn合金获得较好的综合力学性能,应控制锰含量小于7%或在基体中引入适量的亚稳相。     

Sn-Ag-Cu无铅焊料的发展现状与展望

Sn—Ag—Cu系无铅焊料由于具有良好的焊接性能和使用性能，已逐渐成为一种通用电子无铅焊料；综述了Sn-Ag—Cu系焊料从无到有、从二元发展至二三元乃至多元的发展历程，及其研究现状和当前应用较多的几个典型成分的各自应用水平，对当前Sn-Ag-Cu系焊料的熔化温度、润湿性、组织结构和力学性能研究方面以及存在的超电势问题、抗氧化和抗腐蚀性不足、使用的可靠性等主要问题作了总结，并根据国情对其在国内外的发展前景作了预测和展望，提出在发展无铅焊料过程中需要着重注意研究的几个方面，并指出今后较长一段时间内不会出现某一种无铅焊料能像Sn-Pb系那样独断电子封装行业的状态。     

添加钇对TiAl合金组织和性能的影响

设计并熔炼了成分为(Ti₅₀Al₅₀)_100-xY_x(x(atom)=0~2.0%)的合金,用金相显微镜、扫描电镜、三点弯曲试验等手段,研究了添加钇(Y)对TiAl合金显微组织和力学性能的影响。结果表明:钇的添加能改变TiAl合金显微组织,使γTiAl合金晶粒细化,促进γ+α₂片层状组织的形成。适量钇的添加能降低TiAl合金中O、N等间隙原子含量并增加TiAl合金的室温抗弯强度和塑性;当钇的添加量超过其在TiAl合金中的固溶度时,将形成新的Ti-Al-Y三元化合物,反而会降低TiAl合金的室温强度和塑性。     

碳纳米管对镁锌合金组织及性能的影响

采用钟罩浸块铸造法制备了不同碳纳米管含量的镁锌合金铸锭,经热挤压后制备出不同碳纳米管含量变形镁锌合金,研究碳纳米管作为增强材料加入到不含铝的镁锌二元合金中,对其组织和性能产生的影响。利用光学显微镜、扫描电镜及拉伸强度实验机对其显微组织形态及力学性能进行了分析。结果表明,碳纳米管的加入能够显著细化合金铸锭的晶粒起到了细化树枝晶二次枝晶臂间距和转变晶体生长方式的作用,且经过热挤压变形后组织变得更加均匀细小,具有细晶组织;碳纳米管对热挤压镁锌合金的力学性能有增强作用,提高了镁锌合金的抗拉强度、屈服强度、延伸率,当加入量为1.0%时,分别达到最大值219.740,215.969 MPa,27%,其中以延伸率的提高最为显著,抗拉强度和屈服强度值趋于稳定,可得碳纳米管加入到镁锌合金中,起到了较好的复合效果,对晶粒和晶界起到细化和强化的作用,使得该材料具有较高塑形的同时没有降低其强度;合金的断裂特征为典型韧性断裂,有较深的圆形韧窝和撕裂棱组成,碳纳米管与基体合金结合紧密,在拉伸断口处的白色须状物质即为表面被基体合金包覆的碳纳米管。     

退火对Al-Mg-Mn-Zr-Er合金冷轧板组织与性能的影响

制备了Al-6.0Mg-0.7Mn-0.1Zr-0.3Er合金冷轧板材,并对板材进行了不同退火温度和不同退火时间的退火试验,测试退火处理后的合金显微硬度,并采用TEM对合金显微形貌进行分析.结果表明:合金在低于250℃退火时,主要发生回复现象,合金再结晶起始温度为250℃,再结晶终了温度为325℃,且在175℃长时间退火合金易于沿胞状组织的胞壁析出Al3Mg2相.合金中复合添加Er和Zr形成细小弥散的Al3 (Er,Zr)质点,与基体共格,可钉扎位错,稳定亚结构,阻碍亚晶长大及晶界的迁移,从而抑制合金的再结晶,提高合金的热稳定性.     

Co含量对硬质合金组织和性能的影响

采用粉末冶金工艺制备了不同Co含量的硬质合金材料.在常温下测量了材料的力学性能,并通过XRD、SEM等方法对材料的相结构、组织形貌等进行了分析.结果表明,随着co含量的增加,显微组织中粘结相Co的平均自由程λy,增加,WC晶粒邻接度C降低,材料的抗弯强度上升而硬度下降.     

Effects of Tungsten Addition on the Microstructure and Mechanical Properties of Microalloyed Forging Steels

In the current study, the effects of tungsten (W) addition on the microstructure, hardness, and room/low [223 K and 173 K (?50 °C and ?100 °C)] temperature tensile properties of microalloyed forging steels were systematically investigated. Four kinds of steel specimens were produced by varying the W additions (0, 0.1, 0.5, and 1 wt pct). The microstructure showed that the addition of W does not have any noticeable effect on the amount of precipitates. The precipitates in W-containing steels were all rich in W, and the W concentration in the precipitates increased with the increasing W content. The mean sizes of both austenite grains and precipitates decreased with the increasing W content. When the W content was equal to or less than 0.5 pct, the addition of W favored the formation of allotriomorphic ferrite, which subsequently promoted the development of acicular ferrite in the microalloyed forging steels. The results of mechanical tests indicated that W plays an important role in increasing the hardness and tensile strength. When the testing temperature was decreased, the tensile strength showed an increasing trend. Both the yield strength and the ultimate tensile strength obeyed an Arrhenius type of relation with respect to temperature. When the temperature was decreased from 223 K to 173 K (from ?50 °C to ?100 °C), a ductile-to-brittle transition (DBT) of the specimen with 1 pct W occurred. The addition of W favored a higher DBT temperature. From the microstructural and mechanical test results, it is demonstrated that the addition of 0.5 pct W results in the best combination of excellent room/low-temperature tensile strength and ductility.     

Effects of TMCP Parameters on the Microstructure and Mechanical Properties of Nb-Bearing Spring Steel

The effects of TMCP parameters,such as finish rolling temperature and cooling rate on the microstructure and mechanical properties of Nb-bearing spring steel were investigated by thermal simulation,quantitative metallography and tensile test.And the precipitation in Nb-bearing spring steel was analysis by electron microscopy.Experimental results indicate that the higher finish rolling temperature or the more rapid cooling rate in a given range,the less the proeutectoid ferrite content and the thinner the interlamellar spacing is.Reasonably higher finish rolling temperature followed by properly higher cooling rate is suggested to improve the mechanical properties of Nb-bearing spring steel.Micro-addition of niobium decreases the proeutectoid ferrite content and the interlamellar spacing and leads to forming degenerated pearlite.The precipitation of size range ～20-50 nm in Nb-bearing spring steel occurred at the lamellar ferrite of pearlite and the proeutectoid ferrite.     

Effects of Trace Amount Modified SiC Nanoparticles and Electromagnetic Stirring (EMS) on Microstructure and Mechanical Properties of 7055 Aluminum Alloy

The effects of trace amount modified SiC nanoparticles and electromagnetic stirring(EMS)on mierostructures and mechanical properties of 7055 aluminum alloy are investigated experimentally.The result shows that the original developed coarse dendrite and columnar with obvious orientation microstructure turns into homogeneous equiaxed microstructure with the application of trace amount modified SiC nanoparticles and EMS.A minimum grain size is 96μm and has been observed when the addition of modified SiC nanoparticles is 0.05%and the current of EMS is 100A.The ultimate tensile strength is increased by 15.8%and the elongation is improved by 50%compared to those without modified SiC nanoparticles and EMS.Moreover,the compound effects of trace amount modified SiC nanoparticles and EMS is discussed to explain the mechanisms of grain refinement and mechanical properties on 7055 aluminum alloy.     

Unraveling the Initial Microstructure Effects on Mechanical Properties and Work-Hardening Capacity of Dual-Phase Steel

Ferritic-martensitic, dual-phase (DP) microstructures with different size, morphology, and distribution of martensite were produced by altering the initial microstructures using heat treatment and thermomechanical processing routes. It was revealed that the strength, ductility, and work-hardening rate of DP steels strongly depend on the volume fraction and the morphology of the martensite phase. In this regard, the fine-grained DP microstructure showed a high work-hardening ability toward an excellent combination of strength and ductility. Such a microstructure can be readily obtained by intercritical annealing of an ultrafine grained (UFG) microstructure, where the latter can be produced by cold-rolling followed by tempering of a martensite starting microstructure. Conclusively, the enhancement of mechanical properties of DP steels through microstructural refinement was found to be more beneficial compared with increasing the volume fraction of martensite. Finally, it was also demonstrated that the work-hardening rate analysis based on the instantaneous (incremental) work-hardening exponents might be an advantageous approach for characterizing DP steels along with the conventional approaches.     

Effects of Zn on Microstructure Modification and Mechanical Properties Improvement of Al-Si-Cu-Mg Alloys

Metallurgical and Materials Transactions A - In this research, the influence of Zn on the microstructure and mechanical properties of Al-Si-Cu-Mg alloys under different solidification rates was...     

Effects of Thermomagnetic Treatment on Microstructure and Mechanical Properties of Rolling Bearing Steel

 The influence of thermo-magnetic treatment of rolling-bearing steel on some its metallurgical and mechanical properties was investigated. The heating and/or cooling processes of the sample occurred in a magnetic field having certain intensities. The XRD patterns of rolling-bearing steel sample exhibited a beneficial effect of the magnetic field on the structure, phase transformation and tension state. It was found an increased reliability of rolling tribomodel made from thermo-magnetic treated steel when it was subjected to the fatigue tests.     

退火工艺对温轧AZ31板组织、织构及性能的影响

研究了退火温度为573K时,退火时间及组织、织构变化对AZ31温轧薄板性能的影响。分析结果表明,退火时间为60min时,变形组织得到很大的改善,（0002）面硬取向有所减弱,能够获得较好的综合力学性能;进一步延长退火时间到120min,等轴状的晶粒变得更加细小均匀,新的织构组分有所增加,塑性进一步改善。     

钨含量对Mo-W合金板材组织及力学性能的研究

Mo-W合金因为高熔点、低电阻率及优良的高温性能,在工业高温炉、电子光源和平板显示等诸多领域中已得到广泛应用.研究通过采用粉末冶金及轧制变形的工艺制备出Mo-W合金板材,研究了添加不同钨含量对Mo-W合金板材退火组织形貌演变及高温力学性能的影响.结果表明:轧制变形后的Mo-W合金板材与通过理论计算得到的密度值基本一致,...     

生产工艺对65Mn冷轧钢带组织性能的影响

对不同生产工艺下冷轧态及退火态65Mn钢带的组织和退火态钢带的力学性能进行了分析。未经退火的65Mn钢冷轧时,珠光体组织以弯曲变形为主,随着总变形率的增加,珠光体弯曲变形减少,片层细化变形成为主要变形方式;经预退火的65Mn钢冷轧时,珠光体组织变形均以细化变形为主。采用原料经预退火后再进行冷轧的工艺生产的65Mn退火钢带组织均匀,力学性能稳定,塑性较好。     

添加微量稀土元素对Sn-Ag-Cu系无铅焊料性能的影响

以Sn-3．0Ag-0．5Cu（质量分数，％）焊料为母合金，探讨了微量稀土元素Ce、Er、Y和Sc对Sn—Ag—Cu合金物理性能、润湿性能以及力学性能的影响。试验结果表明：稀土元素对焊料的性能有不同的影响，添加微量Ce元素可以更好地改善焊料综合性能。