等径转角挤压及退火后oCr13铁素体不锈钢的微观结构和力学性能

研究了固溶态0Cr13铁素体不锈钢经室温2道次等径转角挤压(ECAP)及退火处理后的微观结构和力学性能.光学显微镜和透射电镜观察表明,经ECAP挤压变形和650—750℃退火后,样品发生部分再结晶,内部残留约10%—35%(体积分数)均匀分布的岛状超细晶基体.统计表明,再结晶晶粒和超细晶晶粒尺寸呈双峰分布,平均晶粒尺寸分别为5.1—8.3μm和418 525 nm.拉伸和冲击测试结果表明,优选的ECAP挤压变形+700℃退火处理工艺,能够使实验钢获得与常规使用态(锻后700℃退火)相当的冲击韧性(212 J/cm~2),以及比后者更高的屈服强度、均匀塑性和静力韧度(分别提高10%,35%和70%).组织细化和应变硬化能力的提高是造成挤压后退火样品综合力学性能提高的原因.     

室温等径转角挤压对18Ni(C-250)马氏体时效钢微观组织和拉伸性能的影响

采用等径转角挤压（ECAP）工艺在室温下对18Ni（C-250）马氏体时效钢进行单道次冷变形.对比固溶处理试样480℃时效曲线、固溶+ECAP处理试样的460和480℃时效曲线发现,一道次ECAP变形及随后的时效处理能够使马氏体时效钢的峰值时效时间明显缩短,峰值强度提高约100 MPa.结构分析表明,ECAP态实验钢的马氏体板条宽度为100—200 nm,随后的时效过程对马氏体板条宽度影响不大,而ECAP工艺对棒状δ-Ni3Mo相析出尺寸有显著影响.统计结果表明,经4 h时效处理后.固溶+480℃时效态、固溶+ECAP+480℃,460℃时效态的δ-Ni₃Mo宽度（直径）分别为4.92,12.33和3.54 nm.此外,ECAP工艺还促使18Ni马氏体钢中δ-Ni3Mo相在时效后期加速分解,使强度迅速衰减.     

等径弯曲通道变形对T250马氏体时效钢的组织和性能的影响

采用等径弯曲通道变形(ECAP)工艺在室温下对固溶态的T250马氏体时效钢以C方式进行了2道次的变形,通过金相显微镜﹑透射电镜及力学性能的测试,研究了多道次ECAP变形对T250马氏体时效钢组织和性能的影响。结果表明,ECAP变形能获得较好的晶粒细化效果,经过2道次的ECAP变形后,马氏体板条变为更窄的带,板条宽度由原始的0.8μm减小到0.2μm,板条内位错密度增加,畸变严重。经2道次室温ECAP挤压变形后,马氏体时效钢的显微硬度从336.3 HV提高到419.8 HV,硬度提高24.7%,并且1道次挤压后硬度的增幅明显大于2道次。     

0Cr13铁素体不锈钢等径转角挤压变形与再结晶组织和性能

研究了0Cr13铁素体不锈钢经等径转角挤压(ECAP)变形和退火处理后的微观组织和力学性能.金相观察表明,变形态0Cr13钢经650～800℃退火1h后,内部形成平均晶粒尺寸为10 μm左右的再结晶组织.同时,力学性能测试表明,退火温度对变形态0Cr13钢的力学性能影响显著,随退火温度由650℃升高到800℃,再结晶组织的发展导致对应的强度、硬度下降,而塑性则逐渐改善.结果表明,优选的ECAP变形+700℃×1h退火工艺,可使实验钢获得最佳的强度-塑性配比.     

不同工艺退火后TC4合金的力学性能

研究了不同退火工艺对TC4合金力学性能的影响。结果表明,经普通退火的TC4合金的短时力学性能要明显好于经β退火的TC4合金,其抗拉强度高出约100 MPa,屈服强度高出约80 MPa,伸长率高出约60%。经β退火后的TC4合金的断裂韧度为100~120 MPa·m1/2,而普通退火态的TC4合金仅有80~90 MPa·m1/2。分析表明,经普通退火得到的显微组织比经β退火处理得到的篮网组织有着更好的强度和塑性,而篮网组织可以使裂纹扩展路径变长,显著提高了TC4合金的断裂韧度值。同时,得到了TC4合金屈服强度与断裂韧度值的函数表达式,发现TC4合金的屈服强度与断裂韧度值的平方成反比。采用此函数关系表达式计算出的KIC值在KIC的实测值范围内,为TC4合金断裂韧度检测结果的可靠性提供了一种判断方法。     

退火对冷轧Al0.2CoCrFe2Ni高熵合金组织和力学性能的影响

研究了不同温度退火对80%冷轧Al_0.2CoCrFe₂Ni高熵合金显微组织和力学性能的影响。使用X射线衍射仪(XRD) 、电子背散射衍射仪(EBSD)、微控电子万能试验机分别对合金进行了晶体结构、织构类型和力学性能的表征。结果表明,合金在铸态、轧制态以及退火态都表现为稳定FCC晶体结构。合金铸态下呈现典型的树枝晶组织,经80% 轧制后出现了明显的轧制变形带,在随后的退火过程中发生再结晶,其再结晶晶粒体积分数及其晶粒尺寸随着退火温度的升高而增加。合金经过80%轧制后主要表现为(111)<112>织构,其织构强度随着退火温度的升高而降低。80%轧制使Al_0.2CoCrFe₂Ni合金获得较大的抗拉强度(1005 MPa)和较低的塑性(10%), 随着退火温度的提高,合金的强度降低塑性增强,并在700 ℃退火时合金获得最佳的综合力学性能,该过程主要取决于合金中的位错密度、再结晶体积分数和晶粒尺寸及其再结晶织构的演变。     

工业纯锆ECAP单道次变形组织与性能研究

室温下采用常规等径弯曲通道变形(ECAP)模具(通道夹角90°,内圆角20°)成功实现工业纯锆ECAP单道次变形。通过金相显微镜、透射电子显微镜(TEM)、X射线衍射(XRD)及单向拉伸实验等测试方法,研究ECAP变形后工业纯锆的组织与性能。研究结果表明:工业纯锆经过通道夹角为90°模具单道次ECAP变形后,晶粒显著破碎,屈服强度和抗拉强度分别提高到397和536 MPa,增幅分别为~43%和~53%;其硬度值也由原始样的1050 MPa提高到了约1550 MPa;材料仍保持有较好的延伸率,延伸率为21.2%。TEM结果显示工业纯锆单道次ECAP变形后试样有大量的板条、位错及位错胞存在。XRD结果表明经ECAP变形后,工业纯锆原始的基面织构和锥面织构转变成了柱面织构。     

剧塑性变形及退火后Mg-Li合金的组织与力学性能

采用剧塑性变形工艺(等通道转角挤压和轧制)以及随后的短时间退火制备高性能Mg-Li合金,通过显微组织观察、扫描电镜分析、X射线衍射仪测试和室温拉伸测试等研究变形前后合金组织、力学性能及强化机制。结果表明:合金铸态晶粒粗大,主相为β相,α相分布于β相的晶界以及晶内;同时,晶内存在大量Al2Y和AlLi析出相。由于动态回复作用显著,合金变形时并未发生明显的动态再结晶现象;经短时间退火后,合金组织发生完全再结晶,其晶粒细化至27.1μm(12pra工艺,即等通道转角挤压、轧制及退火)。铸态合金的抗拉强度和伸长率分别为131.1 MPa和47.1%;经12pr(等通道转角挤压及轧制)变形后,合金的伸长率达到90.5%,而抗拉强度稍有提高,这主要受位错协调变形及动态回复作用的影响;退火后合金的伸长率显著降低而强度提高至237.6 MPa(12pra),出现退火致强化现象,其主要的机制是有限位错源强化及晶界强化。     

前处理T艺对Al-Zn-Mg-Cu合金ECAP的影响

研究了退火、固溶、双级时效以及回归(RRA)热处理4种前处理工艺对Al-Zn-Mg-Cu系铝合金多道次等径通道挤压(ECAP)变形过程的影响.试验结果表明,退火态试样在常温下只能进行2道次ECAP变形,而其余3种状态常温下经1次ECAP变形后便发生严重的开裂现象.退火处理后的试样采用523 K温度加热可进行多次ECAP变形,挤压后晶粒明显细化且逐渐向等轴状演化.8道次之后晶粒细化趋于缓和,10道次后等效真应变达到了6.2,晶粒为O.8 μm左右的等轴状.随着挤压道次的增加,试样显微硬度不断增大,且存在定量关系.     

等径角挤压对Fe-18.39Mn合金组织和阻尼性能的影响

采用等径角挤压(ECAP)工艺改变Fe-18.39Mn合金的ε马氏体片形态,进而研究其对合金阻尼性能的影响.在微机控制电液伺服万能实验机上利用自制模具进行ECAP实验,采用倒扭摆测试合金阻尼性能,扫描电子显微镜观察微观组织.结果表明:Fe-18.39Mn合金在300℃进行ECAP后,由于高密度位错的钉扎,阻尼性能丧失;经过600℃退火,没有改变其ECAP后的组织,阻尼性能仍然很低;而在高于700℃的温度退火处理能大量消除高密度位错,并在一定程度上改变ε马氏体片的形态,使ε马氏体片细化,交叉程度降低,进而阻尼性能较未ECAP时得到提高.     

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.     

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。     

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.     

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.     

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.     

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.