热处理过程中Mg-8Gd-3Y-1Nd-0.5Zr合金的组织演变及性能

采用透射电镜、扫描电镜、能谱分析、X射线衍射及力学性能等测试手段,研究热处理工艺对水冷铸造的Mg-8Gd-3Y-1Nd-0.5Zr(质量分数)合金显微组织、力学性能和耐腐蚀性能的影响。合金铸态显微组织由α-Mg、Mg(Gd,Y)相、富Zr小颗粒相和β-Mg_(24)Y_5网状共晶组成。在520℃固溶24 h后,合金中共晶相固溶进基体,固溶演变过程为α-Mg+β-Mg_(24)Y_5相+Mg(Gd,Y)→过饱和α-Mg固溶体+Mg(Gd,Y)相。225℃时效,合金的析出序列为Mg(S.S.S.S)→β″(DO19)→β′(CBCO)→β_1(FCC)→β(FCC),时效24 h达到峰时效态,合金的室温抗拉强度达到231MPa,伸长率为3.4%。时效处理能提高合金耐腐蚀性能,225℃时效72 h时合金析出稳定β(FCC)相,平均析氢速率最小,为0.22 mL/(cm~2·h),合金的耐腐蚀性能最强。     

热处理对选区激光熔化成形M2052合金组织性能的影响

目的综合提升选区激光熔化(Selective Laser Melting,SLM)成形M2052锰铜合金的力学性能。方法利用SLM技术成形M2052锰铜合金,并通过固溶、时效及固溶+时效等热处理方法对其成形态组织进行调控。通过扫描电子显微镜和X射线衍射仪,对合金的显微组织、晶粒形貌、拉伸断口形貌及物相组成进行分析,并通过拉伸性能、冲击性能测试,分别评价SLM成形及热处理后的屈服强度、抗拉强度、延伸率和冲击韧性。结果 SLM成形的M2052合金经过固溶处理后,形成了典型的类孪晶结构;时效处理后的组织和SLM成形态类似,形成了细微的亚孪晶组织;固溶+时效处理后,类孪晶组织粗大。四种状态的显微组织均由单相γ固溶体组成,时效态和固溶+时效态析出了α-Mn相,但时效态析出含量较多。SLM成形态具有较高的抗拉强度σb和屈服强度σp0.2(636 MPa和548 MPa),时效处理能提高合金的σb和σp0.2(707MPa和570MPa),但是冲击韧性和延伸率(5.5J和8.5%)较差;而固溶处理能显著提高合金的冲击韧性和延伸率(23.5 J和22.25%)。综合比较,固溶+时效态试样具有最好的力学性能(冲击韧性为17 J,延伸率为10.8%,σb为503 MPa和σp0.2为322.5 MPa)。断口分析表明,四种状态下均为韧性断裂。结论固溶+时效热处理可以在存在单相γ固溶体条件下析出少量的α-Mn相,综合提升锰铜合金的力学性能。     

Cu对Mg-9Zn合金显微组织及性能的影响

利用光学显微镜、扫描电子显微镜和力学性能试验机等研究了Mg-9Zn-xCu(x=0,1,3)合金铸态和固溶时效后的组织和力学性能。结果表明:随着Cu含量的增加,晶粒逐渐细化,热处理后力学性能显著提高,延伸率逐渐上升。Cu含量为1%时合金抗拉强度最大,在410℃固溶16 h,160℃时效20 h后,抗拉强度和延伸率为299 MPa和12.06%,较铸态时213MPa和10.7%提高了40.38%和12.71%,但延伸率较固溶处理后下降了26.79%。合金铸态拉伸断口出现一定程度的韧窝,具有韧性断裂特征。热处理后,分布在晶界的析出相周围环绕着大量塑性区,塑性变形能力增强。     

热处理对喷射成形超高强Al-Zn-Mg-Cu系铝合金的影响

研究了2种不同热处理方式对喷射成形超高强度Al-Zn-Mg-Cu系铝合金的显微组织和力学性能的影响.观察了沉积态、挤压态、固溶及时效处理后样品的显微组织,对经时效处理的样品进行了力学性能测试.结果表明:沉积态合金晶粒均匀细小;挤压态合金存在大量的第二相颗粒,为富铜相;固溶处理后,合金出现了再结晶现象.在T6条件下,采用常规470℃单级固溶和时效处理,其抗拉强度仅为710 MPa,延伸率为6.5%;采用双级固溶和时效处理,其抗拉强度超过800MPa,延伸率达到9.3%.     

Mg-11Gd-3Y合金组织与力学性能分析

采用XRD、SEM和拉伸力学性能测试方法,分析了铸态和固溶时效态Mg-11Gd-3Y合金的显微组织和力学性能。结果表明,热处理没有改变Mg-11Gd-3Y合金相的组成,合金铸态和固溶时效态组织均由α-Mg基体、Mg_5Gd和Mg_(24)Y_5相组成。固溶时效态合金的强化机制主要为固溶强化和时效强化,其最大抗拉强度为230 MPa,比铸态合金提高了12%。     

热处理工艺对Mg-6Zn-2.5Cu镁合金显微组织和力学性能的影响

利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和力学试验机等研究了铸造Mg-6Zn-2.5Cu合金在铸态、固溶和时效处理下的显微组织和力学性能。结果表明:合金的铸态组织主要由α-Mg和(α-Mg+MgZn2+Mg2Cu+CuZnMg)共晶相组成。在455℃固溶12~36 h时,随着时间增加,固溶效果逐渐增强,且在20 h时合金获得了较理想的显微组织及218 MPa的抗拉强度和8.68%的伸长率。随后在180℃时效6~72 h后,合金的拉伸性能随时效时间的增加呈先增加后减小的趋势,其中时效24 h时后,合金的抗拉强度和硬度达到峰值,分别为249.5 MPa和64.6 HV0.1,比铸态的分别提高了66.5 MPa和26.29%,伸长率在时效12 h时后达到了峰值6.72%。铸态合金的断裂方式以沿晶断裂为主,时效处理后合金的断裂方式为准解理断裂。     

热处理工艺对Mg-6Zn-2Sm-0.4Zr镁合金显微组织和力学性能的影响

通过在Mg-6Zn合金中添加0.4%Zr和2%Sm(质量分数)制备出一种新型Mg-6Zn-2Sm-0.4Zr合金;利用光学显微镜(OM)、扫描电镜(SEM)及能谱仪(EDS)、X射线衍射仪(XRD)、显微硬度及力学性能测试研究铸造Mg-6Zn-2Sm-0.4Zr合金在铸态、固溶、时效处理下的显微组织和力学性能的变化。结果表明:合金铸态组织主要由基体α-Mg、晶界处呈连续或半连续分布的(α-Mg+Mg_2Zn_3+Mg_(41)Sm_5)共晶和晶内孤立的点状相组成。合金在440和450℃固溶12~36 h时间范围内,随着时间和温度的增加,固溶效果逐渐增强。当在450℃固溶28 h时获得了较好的显微组织,抗拉强度为230 MPa,伸长率为9.58%。随后经200℃时效6~48 h后,合金的力学性能明显提高,时效强化效应随时间的延长呈先增加后减小的趋势,其中时效12 h时同时出现了抗拉强度和伸长率的峰值258 MPa和14.43%,比铸态的分别提高44 MPa和90.80%。     

低温固溶及时效处理对TC4合金棒材组织及力学性能的影响

研究了TC4钛合金棒材经650和700℃固溶处理及时效处理后的组织和性能变化。结果表明:对热加工态的TC4钛合金进行650℃的固溶热处理,材料的显微组织和拉伸性能变化不大。经过700℃固溶热处理,TC4钛合金棒材强度明显降低,屈服强度相对于热加工态降低77 MPa,且屈/强比明显低于普通退火。时效热处理后,合金的强度显著提高,400℃时效后抗拉强度达到1020 MPa,相对于热加工态提高53 MPa。显微组织分析表明,热加工后的TC4棒材显微组织由初生α相、次生α相以及残余β相组成。热处理过程中,残余β相中针状α相的溶解与重新析出是影响合金拉伸性能变化的主要原因。     

热处理对Mg-Zn-Sr合金组织与性能的影响

研究了少量Sr(0、0.2%、0.5%、1.0%)的加入对铸态Mg-4Zn合金组织和力学性能的影响,以及热处理对Mg-Zn-Sr合金显微组织与力学性能的影响。结果表明,添加0.5%Sr的铸态合金具有最佳的力学性能,其抗拉强度为161 MPa,屈服强度为82 MPa,伸长率为10.30%。合金经过440℃×18 h固溶处理后,第二相基本固溶进基体中,其抗拉强度为192 MPa,屈服强度为99 MPa,伸长率为14.77%。随着时效时间的增加,MgZn相数量增加,且弥散分布,时效8 h,合金性能较好,其抗拉强度为223 MPa,屈服强度为118 MPa,伸长率为12.06%。时效12 h,Mg_(17)Sr_2相开始大量析出,影响合金性能。     

热处理对锻态2.5%(TiB+TiC)/Ti复合材料组织与性能的影响

研究了热处理条件对锻态2.5%(TiB+TiC)/Ti(体积分数)复合材料显微组织和力学性能的影响。结果表明:固溶时效处理对复合材料的基体组织特征有显著影响,在两相区进行固溶时效处理后,得到等轴和双态组织,随固溶温度的升高,初生α相含量逐渐降低,而β转变组织含量逐渐升高,当固溶温度超过β转变温度时,得到全片层组织。TiB和TiC增强相在热处理过程中较为稳定,形态与分布无明显变化。固溶时效处理后,锻态复合材料的抗拉强度提高而塑性降低,随固溶温度的升高,复合材料的室温抗拉强度和塑性均有明显增加,而650℃下抗拉强度与塑性与室温下表现出相反的规律。复合材料经1050℃/2 h/AC+600℃/6 h/AC处理后综合性能最好,室温抗拉强度为1215.8 MPa,延伸率为3.14%,650℃下抗拉强度为629.9 MPa,延伸率为15.9%。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.