热力参数对Ti-17合金等温锻件显微组织和力学性能的影响

研究了富β相的α+β钛合金Ti-17,毛坯的原始状态(如组织形态、晶粒大小、均匀性)、热加工工艺路线、热处理制度及工艺参数对等温模锻件最终显微组织和力学性能的影响.结果表明,Ti-17合金等温锻造之前的自由锻预制毛坯对锻件的显微组织、力学性能有明显影响,直接采用晶粒较大的原始棒材在β相区等温锻造,锻件高倍组织中的α相呈鱼骨状,各项力学性能均较差;经自由锻预制坯的等温锻件显微组织细小而均匀,在两相区锻造时,获得细小均匀的等轴α组织;在β相区锻造时,获得细小均匀的网篮状α组织,各项力学性能满足要求.

含铜球墨铸铁的微观组织和力学性能研究

为满足ASTMA 536标准中80-55-06级球墨铸铁力学性能要求,冶炼了不同含铜量的球墨铸铁,检测其显微组织、力学性能、硬度及断口形貌。结果发现,不同含铜量的球墨铸铁的力学性能和显微组织也不相同,包括石墨球的数量、石墨球的直径、铁素体和珠光体的含量。此外,铜含量在0.3%?0.5%的球墨铸铁的力学性能符合ASTM A536标准中80-55-06级球墨铸铁的要求。

基于原子力显微技术的混合料中沥青微尺度性能测试方法

以沥青混合料试件为研究对象,探讨了原子力显微样本的制备方法.选取最大纵向起伏度和表面粗糙度两个指标对不同储存条件下的样本制备效果进行评定,提出采用低温冷冻措施保证AFM(atomic force microscope)样本平整度的制样方法;利用原子力显微技术的力学性能量化模块AFMQNM(atomic force microscope-quantitative nano mechanical),选取沥青胶浆区域3个典型的观测区域,进行原子力显微测试及微尺度力学性能量化表征.研究结果表明,"冷冻保存、低温切割"的混合料试件样本制备方法能够满足AFM技术的观测要求;AFM-QNM技术可以在混合料试件中直接测试沥青(胶浆)和矿质集料的模量和黏附性质,可有效区分不同的材料组分.

Ti_(50)Cu_(42)Ni_8非晶合金力学性能与晶化组织的研究

采用铜模喷注法成功制备出成本较低直径为2 mm的Ti50Cu42Ni8大块非晶合金,对其力学性能及铸态与晶化显微组织进行了研究。结果表明:Ti50Cu42Ni8非晶合金具有优异的力学性能,压缩断裂强度可达2008 MPa,弹性模量为100 GPa,非晶样品的断裂面与轴向成45°,断口出现河流状脉纹及熔滴。其铸态显微组织为无特征组织,480℃和650℃退火后分别出现条状和梅花状晶态相。

电厂主蒸汽管的微观性能分析

采用纳米显微力学探针 (NanoIndenterII)及透射电子显微镜 ,对使用不同时间的低合金耐热钢(12Cr1MoV)电厂主蒸汽管道的组织及性能进行分析研究。结果表明 :随着运行时间的延长 ,细小碳化物颗粒不断在铁素体基体中析出 ,使基体强化 ,管样显微硬度提高 ;但在晶界出现聚集长大的碳化物。若运行时间过长 ,最终可能因晶界碳化物的粗大而产生沿晶断裂。本文分析的已使用 30× 10 4 h的主蒸汽管道仍能继续运行使用。

热反挤压变形对n-SiC_p/2024复合材料组织与性能的影响

利用半连续铸造-热反挤压工艺制备了n-SiCp/2024复合材料棒材。通过金相组织观察(OM)、扫描电镜(SEM)、室温力学性能以及电导率测试等手段,研究了该复合材料在热反挤压前后的显微组织、力学性能与电导率的变化情况。结果表明:复合材料铸锭中粗大第二相沿晶界非连续分布,Cu、Mg元素偏聚显著,大多数n-SiCP偏聚在晶界处,少量分布在晶内;热挤压变形后,n-SiCp团聚现象显著消除,Cu、Mg元素及n-SiCP分布趋于均匀,n-SiCp及破碎第二相沿热挤压方向呈纤维状分布;拉伸实验结果表明,热挤压后复合材料的强度及塑性显著提高;热挤压后,复合材料的电导率低于基体合金。

Effect of annealing temperature on microstructure and mechanical properties of Mg-Zn-Zr-Nd alloy with large final rolling deformation

In this study,the Mg-3Zn-0.5Zr-χNd(χ=0,0.6)alloys were subjected to final rolling treatment with large deformation of 50%.The impact of annealing temperatures on the microstructure and mechanical properties was investigated.The rolled Mg-3Zn-0.5Zr-0.6Nd alloy exhibited an ultimate tensile strength of 386 MPa,a yield strength of 361 MPa,and an elongation of 7.1%.Annealing at different temperatures resulted in reduced strength and obviously increased elongation for both alloys.Optimal mechanical properties for the Mg-3Zn-0.5Zr-0.6Nd alloy were achieved after annealing at 200℃,with an ultimate tensile strength of 287 MPa,a yield strength of 235 MPa,and an elongation of 26.1%.The numerous deformed microstructures,twins,and precipitated phases in the rolled alloy could impede the deformation at room temperature and increase the work hardening rate.After annealing,a decrease in the work hardening effect and an increase in the dynamic recovery effect were obtained due to the formation of fine equiaxed grains,and the increased volume fraction of precipitated phases,which significantly improved the elongation of the alloy.Additionally,the addition of Nd element could enhance the annealing recrystallization rate,reduce the Schmid factor difference between basal and prismatic slip systems,facilitate multi-system slip initiation and improve the alloy plasticity.

Strength and plasticity improvement induced by strong grain refinement after Zr alloying in selective laser-melted AlSiMg1.4 alloy

In order to enhance the mechanical properties of the selective laser-melted(SLM) high-Mg content AlSiMg1.4 alloy,the Zr element was introduced.The influence of Zr alloying on the processability,microstructure,and mechanical properties of the alloy was systematically investigated through performing microstructure analysis and tensile testing.It was demonstrated that the SLM-fabricated AlSiMg1.4-Zr alloy exhibited high process stability with a relative density of over 99.5% at various process parameters.Besides,the strong grain refinement induced by the primary Al3Zr particle during the melt solidification process simultaneously enhanced both the strength and plasticity of the alloy.The values for the yield strength,ultimate tensile strength,and elongation of the SLM-fabricated AlSiMg1.4-Zr were(343±3) MPa,(485±4) MPa,and(10.2±0.2)%,respectively,demonstrating good strengthplasticity synergy in comparison to the AlSiMg1.4 and other Al-Si-based alloys fabricated by SLM.

Effect of cold rolling deformation on microstructure evolution and mechanical properties of spray formed Al−Zn−Mg−Cu−Cr alloys

The impact of cold rolling deformation,which was introduced after solid solution and before aging treatment,on microstructure evolution and mechanical properties of the as-extruded spray formed Al−9.8Zn−2.3Mg−1.73Cu−0.13Cr(wt.%)alloy,was investigated.SEM,TEM,and EBSD were used to analyze the microstructures,and tensile tests were conducted to assess mechanical properties.The results indicate that the D1-T6 sample,subjected to 25%cold rolling deformation,exhibits finer grains(3.35μm)compared to the D0-T6 sample(grain size of 4.23μm)without cold rolling.Cold rolling refines the grains that grow in solution treatment.Due to the combined effects of finer and more dispersed precipitates,higher dislocation density and smaller grains,the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa,respectively.In comparison to the as-extruded and D0-T6 samples,the yield strength of the D1-T6 sample increases by 415 and 92 MPa,respectively.

Microstructure,interfacial reaction behavior,and mechanical properties of Ti_(3)AlC_(2)reinforced Al6061 composites

The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the addition of3.0 wt.%Ti_(3)AlC_(2)refines the average grain size ofα(Al)in the composite by 50.1%compared to Al6061 alloy.Morphological analyses indicate that an in-situ Al_(3Ti)transition layer of-180 nm in thickness is generated around the edge of Ti_(3)AlC_(2)at 720℃,forming a well-bonded Al-Al_(3Ti)interface.At this processing temperature,the ultimate tensile strength of A16061-3.0 wt.%Ti_(3)AlC_(2)composite is 199.2 MPa,an improvement of 41.5%over the Al6061 matrix.Mechanism analyses further elucidate that 720℃is favourable for forming the nano-sized transition layer at the Ti_(3)AlC_(2)edges.And,the thermal mismatch strengthening plays a dominant role in this state,with a strengthening contribution of about 74.8%.

热处理对K403镍基高温合金组织和性能的影响

采用光学显微镜、扫描电镜对K403镍基高温合金的铸态组织和不同固溶和时效处理后的组织进行了观察,研究了不同固溶和时效处理对K403合金组织、抗拉强度、硬度的影响。结果表明,合金经过1140,1180℃不完全固溶处理后,组织为大小2种尺寸的γ’相;经过1210℃完全固溶处理后空冷,均匀析出0.2μm的γ’相。时效后,合金抗拉强度和硬度得到提高。经1190℃,4h,AC+940℃,16h,AC处理,合金获得最佳的抗拉强度和硬度。经1190℃,4h,AC+980℃,16h,AC处理,γ’相长大到0.6μm,导致合金硬度相对下降。

热机械处理对Ti-6-22-22S合金组织与性能的影响

研究了不同热机械处理工艺及随后的热处理工艺对Ti-6-22-22S(Ti-6Al-2Sn-2Zr-2Cr-2Mo-Si)合金组织、性能的影响.结果表明在β相区加工并在两相区固溶时效处理,可使合金的强度、塑性和断裂韧性达到优良组合.

表面状态对铝锂合金填充式摩擦点焊接头性能的影响

研究了不同表面处理状态对5A90铝锂合金填充式摩擦点焊接头性能的影响。结果表明,母材表面经过化学清洗的试样剪切拉伸抗力最大;表面状态影响搭接界面的有效承载面积,进而影响焊点的剪切拉伸性能,水平界面处的"虚焊"缺陷是降低焊点连接质量的最主要因素。

TC6合金叶片用棒材组织与性能

通过合理的工艺路线锻制出显微组织、力学性能优良的TC6合金叶片用棒材.对锻制出的棒材进行了常规力学性能的测试和显微组织的观察.通过不同的热处理工艺获得不同的组织类型,对不同组织类型和性能进行了讨论.

OT4-0钛合金的组织结构和性能

对不同合金元素含量的OT4-0钛合金棒材的显微组织观察和性能测试发现,添加合金元素Al和Mn使合金强度显著增加,塑性变化不大,Mn对合金的固溶强化作用强于Al;Mn明显细化合金组织,Al对组织的细化作用不明显;Mn对合金的强化起因于固溶和组织细化的双重作用.

添加WC对纳米Si_3N_4陶瓷组织和力学性能的影响

采用热压烧结制备了纳米Si3N4-WC复合陶瓷,研究了WC颗粒的添加对纳米Si3N4陶瓷组织与力学性能的影响。试验结果表明:纳米Si3N4-WC复合陶瓷的基体显微组织由粒径小于100nm的等轴晶粒构成,WC以独立颗粒的形式存在,对显微组织影响不大;纳米Si3N4-WC复合陶瓷的硬度随WC含量的增加而升高,但低于单相纳米Si3N4陶瓷,添加适量的WC颗粒可以提高纳米Si3N4陶瓷的断裂韧性,但对抗弯强度影响不大。

Mg含量对Al-Cu-Mg-Ag合金组织与力学性能的影响

通过室温拉伸、疲劳裂纹扩展速率测试及透射电镜等实验手段,研究Mg含量对Al-Cu-Mg-Ag合金时效析出过程与力学性能的影响。结果表明:随着Mg含量的增加,合金的时效响应速率加快,而强度则先上升后下降,当Cu/Mg比为6时,合金强度最高;Mg含量的提高为主要析出相?相提供了更多的形核位置,使得合金基体中的析出相细小弥散,分布均匀;Cu/Mg比接近4的合金经165℃时效30min处理后,晶内析出大量的Cu-Mg原子团簇,疲劳性能最佳。

Effects of cold rolling and heat treatment on microstructure and mechanical properties of AA 5052 aluminum alloy

The microstructures and mechanical properties of homogenized-rolled AA5052 aluminum alloys with different rolling reductions and following annealing treatments were investigated by optical microscope, scanning electron microscope, X-ray diffractometer, micro-hardness and tensile tests. The results show that with increasing rolling reduction, the equiaxed grains are elongated along the rolling direction obviously, and accumulation of rolling reduction increases the work hardening effect, which results in the enhanced strength and degraded plasticity. When rolling reduction is 87%, the ultimate tensile strength reaches 325 MPa but elongation is only 2.5%. There are much more secondary phase precipitates after annealing treatment. With an increase of annealing temperature, the amount of precipitates increases and work hardening diminishes continuously. The elongation is improved to ~23% but the tensile strength is decreased to 212 MPa after annealing at 300 °C for 4 h, which are comparable to those of as-homogenized alloy.

Microstructure and mechanical properties of Mg,Ag and Zn multi-microalloyed Al-(3.2-3.8)Cu-(1.0-1.4)Li alloys

To develop super-high strength Al-Li alloy,the microstructures and mechanical properties of Mg,Ag and Zn microalloyed Al-（3.2-3.8）Cu-（1.0-1.4）Li alloys（mass fraction） with T8 temper were studied.The results showed that 1%of lower Li content restricted the strengthening effect of increasing Cu content,while simultaneous increase in Cu and Li contents contributed effectively to the enhancement of strength.The alloys were mainly strengthened by plenty of fine and well dispersed TI（Al2CuLi）precipitates.There were also some minor precipitates of θ＇（Al2Cu） and δ＇（Al3Li）,which became less in number density,even disappeared during the aging process.Meanwhile,higher Li content favored the formation θ＇ and δ＇ and a small amount of S＂（Al2CuMg） phases.In addition,strengthening effect and microstructure variation were analyzed through total non-solution mole fraction of Cu and Li and their mole ratio.To obtain Al-Li alloy with super-high strength,the total mole fractions of Cu and Li should be increased,and their mole ratios should also be kept at a certain high level.

Effects of Ce addition on microstructure and mechanical properties of Mg-6Zn-1Mn alloy

The effects of Ce addition on the microstructure of Mg-6Zn-1Mn alloy during casting, homogenization, hot extrusion, T4, T6 and T4＋two-step aging were investigated. The mechanical properties of alloys with and without Ce were compared. The results showed that Ce had an obvious effect on the microstructure of ZM61-0.5Ce alloy by restricting the occurrence of dynamic recrystallization and restraining the grain growth during extrusion and heat treatment subsequently. A new binary phase Mg 12 Ce was identified in ZM61-0.5Ce alloy, which distributed at grain boundaries and was broken to small particles distributed at grain boundaries along extrusion direction during extrusion. The mechanical properties of as-extruded ZM61-0.5Ce alloy were improved with the addition of Ce. The improved tensile properties of as-extruded ZM61-0.5Ce alloy were due to the finer grain sizes as compared to ZM61 alloy. However, the UTS and YS decreased severely and the elongation increased when ZM61-0.5Ce was treated by T6 and T4＋two-step aging. Brittle Mg 12 Ce phase, which was distributed at the grain boundary areas and cannot dissolve into the Mg matrix after solution treatment, became crack source under tensile stress.