Influence of deformation parameters on microstructure and mechanical properties of TA 15 titanium alloy

The influence of deformation parameters including deformation temperature, degree and speed on the microstructure and mechanical properties of TA15 titanium alloy was studied. The volume fraction, size and aspect ratio of primary a phase in deformed TAI 5 titanium alloy were quantitatively characterized. With increasing deformation temperature, the volume fraction and size of primary α phase decrease. The aspect ratio of primary a phase decreases with increasing deformation temperature. The tensile strength of TA15 alloy deformed at 0.1 mm/s is higher than that at 0.3 mm/s. After therlnoforming at 960℃, 0.1 mrn/s, the tensile strength is the highest up to 1 035 MPa and the elongation is 13.5%. When the thermoforming temperature is 1 050℃, the strength and elongation are both relative low, because the microstructure is Widmanstaten structure.     

Effects of returns on composition,microstructure and mechanical properties of GH4169 superalloy

To recycle the returned alloy effectively, effects of returns proportion on alloy composition, microstructure and compression properties of superalloy GH4169 were studied by means of scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and thermal-mechanical simulator. The results show that returns addition has no significant effect on the main alloy elements content and the principle precipitates, but increases the volume fraction of Al_2O_3 inclusions, resulting in the increase of oxygen level of GH4169 alloy. Returns addition does not change the elastic and plastic deformation process at room temperature or at 1,150 °C, but high returns proportion GH4169 alloy shows improved compression strength and yield strength. The alloy with 100% returns shows a maximum compression strength 1,153.45 MPa at room temperature, while the alloy with 80% returns has a maximum value 69.3 MPa at 1,150 °C. Returns addition increases fluctuation range and reduces the stability of yield strength and compression strength of GH4169 alloy at room temperature. It is noted that the volume fraction and the size of Al_2O_3, and the fraction of Laves phase reach their maximum values in the GH4169 alloy with 60% returns, which exhibits maximum yield strength of 516.65 MPa at room temperature and 62.17 MPa at 1,150 °C.     

Inluence of heat treatment on microstructure and tensile properties of a cast Al-Cu-Si-Mn alloy简

Solution and aging treatments are important approaches to improve mechanical properties and microstructure of aluminum-base alloys. In this research, a new type high strength AI-Cu-Si-Mn cast alloy was prepared. The effect of different solution and aging treatment temperatures on microstructure and mechanical properties of the AI-Cu-Si-Mn cast alloy were studied by means of microstructure observation and mechanical properties testing. Results showed that after solution treated at different temperatures for 12 h and aged at 175 ℃ for 12 h, with the increase of the solution temperature, both the tensile strength and the elongation of the alloy firstly increase and then decrease, and reach their peak values at 530 ℃. When the solution temperature is below 530 ℃, the microstructure of the alloy consists of a phase, undissolved e phase and T phase; while when it exceeds 530 ℃, the microstructure only consists of cr phase and T phase. After solution treated at 530 ℃ for 12 h and aged at different temperatures for 12 h, both the tensile strength and the elongation of the alloy firstly increase and then decrease with the increasing of temperature, and reach their peak values at 175 ℃. Therefore, the optimal heat treatment process for the alloy in this study is 12 h solution at 530 ℃ and 12 h aging at 175 ℃, and the corresponding tensile strength is 417 MPa, elongation is 4.0%.     

Effects of calcium addition on as-cast microstructure and mechanical properties of Mg-5Zn-5Sn alloy

The effects of Ca addition on the as-cast microstructure and mechanical properties of the Mg-5Zn-5Sn (mass fraction,%) alloy were investigated.The results indicate that an addition of 0.5%-1.5% (mass fraction) Ca to the Mg-5Zn-5Sn alloy not only refines the as-cast microstructure of the alloy but also causes the formation of the primary and/or eutectic CaMgSn phases with high thermal stability;an increase in Ca amount from 0.5% to 1.5% (mass fraction) increases the amount and size of the CaMgSn phase.In addition,Ca addition to the Mg-5Zn-5Sn alloy improves not only the tensile properties at room temperature and 150 ℃ but also the creep properties.Among the Ca-containing Mg-5Zn-5Sn alloys,the one added 0.5% (mass fraction) Ca obtains the optimum ultimate tensile strength and elongation at room temperature and 150 ℃,however,the alloy added 1.5% (mass fraction) Ca exhibits the optimum yield strength and creep properties.     

Microstructure and properties of ZL205 alloy

The microstructure, precipitate type, precipitate distribution and tensile strength of a ZL205 alloy, before and after ageing treatment, have been studied by means of optical microscopy and transmission electron microscopy. The results showed that the as-cast microstructure of the alloy was made up of α-Al and eutectic phase distributed at the grain boundaries. During ageing treatment, the tensile strength increased at first and then reduced with time, and the highest ultimate tensile strength was found to be around 488.2 MPa.     

Microstructure and mechanical properties of Mg-Zn-Gd-based alloys strengthened with quasicrystal and Laves phase

One kind of Mg3.5Zn0.6Gd-based alloy strengthened with quasicrystals was designed, and the effect of alloying elements on microstructure and mechanical properties of as-cast Mg-Zn-Gd alloy at room temperature and elevated temperatures were studied. The results indicate that MgZnCu Laves phase, which coexists with quasicrystal at grain boundary, emerges with the addition of copper element in Mg-Zn-Gd alloy. The strength of alloys exhibits the parabola curve with the increase of copper content. The alloy with 1.5% （mole fraction） Cu shows better mechanical properties at room temperature： tensile strength 176 MPa, yield strength 176 MPa and elongation 6.5%. The existence of MgZnCu Laves phase can effectively improve the heat resistance and elevated temperature properties of the alloy. The alloy with 1.5% Cu has better mechanical properties at 200℃ ： tensile strength 130 MPa and elongation 18.5%. The creep test of the alloys at 200℃ and 50 MPa for 102 h indicates that Mg3.5Zn0.6Gd alloy reinforced with quasicrystal has better creep properties than AE42, which can be further improved with the introduction of Laves phase in the alloy.     

Influence of annealing and spheroidizing treatment on microstructure and mechanical properties of AZ91 magnesium alloy

The low-strength and high-brittleness of AZ91 cast magnesium alloy mainly result from the coarse divorced eutectic phase.To solve these problems,the annealing treatment of AZ91 cast magnesium alloy was carried out at 415 ℃ and held for 24 h in this study and the alloy was then slowly cooled to room temperature in furnace.The microstructures of the alloy were observed using a metallographic microscope,a transmission electron microscopy and an emission scanning electron microscopy,respectively.The phase analysis was performed using the X-ray diffraction,and the tensile test of the specimen at ambient temperature was performed on a material test machine.The results indicate that the coarse divorced eutectic phase dissolves into the Mg matrix during the isothermal process,and the lamellar β-Mg17Al12 phase precipitates from the magnesium solid solution with a type of pearlite precipitation during furnace cooling.Consequently,the spheroidizing treatment was carried out at 320 ℃ for 20 h following the annealing process and the lamellar β-Mg17Al12 phase was spheroidized.Compared with the as-cast alloy,the strength and ductility of the AZ91 magnesium alloy are increased obviously after annealing treatment;the yield strength and tensile strength are increased to 137.8 MPa and 240.4 MPa from 102.9 MPa and 199.3 MPa,respectively;and the elongation is improved to 6.12% from 4.35%.After being spheroidized,the strength and hardness decrease a little,but the ductility is elevated to 7.23%.The nucleation,growth and spheroidizing mechanism of the lamellar β-Mg17Al12 phase were also discussed.     

Effects of Ca addition on tensile properties and microstructures of hot-extruded AZ91 alloy tube

As-cast AZ91＋XCa （X=0, 0.5%, 1.0%, 1.5%, mass fraction） magnesium alloys were extruded into tube at 380℃ with an extrusion ratio of 6：1. The tensile properties and microstructures of extruded AZ91＋XCa alloy tubes were investigated. The mierostructural observation indicates that Ca can obviously refine both α-Mg grains and Mg17Al12 phase of AZ91 magnesium alloy. XRD analysis shows that the microstructure of AZ91＋0.5Ca alloy consists of a-Mg solid solution and Mg17Al12 phase, while AZ9 I＋1.5Ca alloy contains additionally Al2Ca phase. The tensile experimental results show that for the AZ91 alloy, the addition of Ca has little influence on the ambient temPerature tensile properties but can improve the elevated temperature tensile properties. For the extruded AZ91＋XCa alloys, the elevated temperature tensile strength decreases, and elongation increases with increasing the Ca content. The improvement in elevated temperature tensile strength of the alloy can be attributed to the presence of a Ca-containing phase, which can increase the microstructural stability of the alloy at elevated temperature.     

Transient liquid-phase bonding of superalloy K465 using a Ni-Cr-Fe-B-Si amorphous interlayer alloy

A kind of Ni-Cr-Fe-B-Si system amorphous alloy was used as interlayer in transient liquid-phase bonding(TLP bonding) of polycrystalline superalloy K465.The bonding behavior,microstructure feature and the tensile properties of the joints were investigated.There are B-rich phase and Si-rich phase formed in the center of the seam after bonding at 1210℃ for 30 min.The isothermal solidification is complete after bonding at 1210℃ for 4 h.The relationship of the average width of the remnant eutectic zone and bonding time at 1210℃ is nonlinear.The tensile strength of the bonded joint at room temperature and 900℃ is comparable to that of K465 alloy.     

Effect of thermal processing on microstructure and mechanical properties of AZ80 magnesium alloy

The influences of deformation temperature and deformation degree on the microstructure and mechanical properties of AZ80 magnesium alloy were investigated by the adoption of isothermal plain strain compression experiment.The results show that thermal compression processing can refine the grain size and the tensile strength of all the deformed AZ80 magnesium alloys is increased to the maximum of 320 MPa.With the increasing of deformation temperature,the tensile strength decreases;with the increasing of th...     

40CrNi2Si2MoVA钢的大气应力腐蚀行为

用单轴拉伸试样和预制裂纹试样研究40CrNi2Si2MoVA高强度钢在典型大气环境下的抗应力腐蚀性能.施加应力后的试样分别暴露于北京、青岛、万宁3个不同的大气试验站.研究表明:40CrNi2Si2MoVA钢的抗应力腐蚀性能取决于环境,在海洋性环境下应力腐蚀性较高.扫描电子显微镜微观分析表明裂纹起始于表面的腐蚀点,并向试样内部扩展,为沿晶开裂,有二次裂纹存在.随着应力水平的增大,二次裂纹明显增加.     

SnO2掺杂对TiO2压敏电阻器性能的影响

采用固相合成法制备了SnO2掺杂的TiO2基压敏电阻系列样品，并通过XRD和SEM分析，以及Ⅰ-Ⅴ矿曲线测量对材料的结构和电学性能进行了研究。结果表明：SnO2的掺杂抑制了晶粒的生长，晶界相含量增加。电性能测试结果显示，SnO2的掺杂量在0～1．5mo1％内，击穿场强随SnO2掺杂量的增加单调递增；非线性系数先增加后又减小，掺杂量为0．8mol％的样品具有最大的非线性系数（α=8.3）。并对以上的实验结果从理论上给予了分析。     

TiC-Mo2FeB2系复合涂层的组织与性能

用真空液相烧结法在钢基体表面制备了TiC-Mo2FeB2系复合涂层,测定了TiC-Mo2FeB2系复合涂层-钢基体界面结合强度及界面结合区的显微硬度变化,研究了复合涂层的显微组织与界面微观结构和界面区元素分布。结果表明,涂层与钢基体之间具有较高的结合强度,当TiC含量为8%时结合强度最高为820.66 MPa,显微维氏硬度为12.06 GPa,在复合涂层-钢基体结合界面处,存在一个由涂层高硬度到钢基体低硬度的狭窄过渡区,并且两相之间形成了良好的冶金结合。     

壳体用钢30CrMnSiNi2A的强韧化热处理研究

针对壳体用低合金超高强度钢30CrMnSiNi2A，通过贝氏体区短时间等温淬火得到马氏体＋贝氏体＋少量残余奥氏体的复合组织，使强度和韧性得到良好配合。实验考察了等温时间的变化对钢力学性能的影响，得出较优的等温时间范围。     

聚丙烯材料在硫酸钾装置中的应用

本文介绍了聚丙烯材料的性能、特点，利用其特点将聚丙烯材料用于管道或衬里管道，以输送腐蚀和磨蚀介质，结合使用条件分析了在使用温度下的腐蚀、磨蚀、强度使用寿命等问题。     

Effects of load mode on mechanical properties of ZrO_2(2Y)/TRIP steel composites

1　INTRODUCTIONArmourmaterialsbearthehigh speedstrikingload.Soitisbeneficialtotheballisticpropertiesofthematerialsbyimprovingtheabsorbedenergyunderdynamicloadorinducingthe phasetransformationstrengtheningduringtheabsorbingenergy pro cess[1,2 ] .Transformationinduced plasticitysteel(TRIP)hasthegoodtransformationplasticity ,highroomtemperaturestaticstrengthand goodweldingpropertyandisa promisingarmourmaterial[3,4 ] .ZrO2 hashighstrength ,highhardnessand goodchemicalconsistentpropertieswhe…     

NL-2型粘结力试验仪

乳化沥青稀浆封层是一种经济可靠的路面处治方法，以先进可靠的配合比设计和试验检测手段为基础，介绍NL－2型粘结力试验仪的工作原理和结构特点，以及对路面乳化沥青稀浆封层混合料粘结程度的测试方法等，有助于我国乳化沥青稀浆封层技术的应用和发展。     

ZrO2与25CePO4／ZrO2材料的坯体无压连接

以CePO4与Ce-ZrO2等比例混合的含粘结剂的料浆为连接材料，在坯体状态下无压连接了可加工CePO4／Ce—ZrO2陶瓷与Ce-ZrO22陶瓷。对影响接点性能的工艺条件进行了讨论，材料的烧成温度和保温时间会明显影响连接效果，对25CePO4．Ce—ZrO2／Ce-ZrO2体系，在1450℃保温120min左右时，可实现最佳的连接效果。接点SEM分析表明，25CePO4/Ce—ZrO2和Ce-ZrO2连接体系中可形成结构均匀的扩散接点区域，其微观结构与母体材料的基本一致，接点的平均抗弯强度也与母体材料相似。用坯体无压连接法适合复杂形状本体或异体组合陶瓷构件，其工艺流程简单，加工成本低廉。     

TA2-1060-TA2复合板爆炸焊接试验及性能测试

为了解决钛-铝在爆炸焊接过程中可焊性低并容易产生脆性金属间化合物等技术难题，选用低爆速粉状乳化炸药为试验用药，下限装药厚度和上限基复板间距为工艺参数，成功获得了100%复合的“1 + 14 + 1”TA2 - 1060 - TA2双面金属复合板. OM， SEM， EDS测试结果表明，复合板界面呈良好小波状结合；基复板流在波峰阻挡以及复板挤压作用下形成漩涡结构，其内部存在包覆熔融金属的铸锭组织；结合界面附件发生不同程度的元素扩散. 力学测试结果表明，复合板的弯曲强度为288 MPa、抗拉强度为165.5 MPa、界面处显微硬度峰值为227 HV，满足工业生产要求.     

淬火与回火间的时效对1Cr17Ni2钢组织及屈服强度的影响

研究分析了1Cr17Ni12钢在淬火与回火间进行时效及其组织及屈服强度的影响。认为淬火后，进行时效处理，然后再进行回火，可明显减少残留奥氏体量，提高1Cr17Ni12钢的屈服强度及屈强比。