高硼钢的微观组织和性能

采用铸造和粉末冶金工艺制备硼含量分别为1.04%、1.50%和1.86%的高硼钢,研究了合金的微观组织、物相、硼元素在组织中的分布和物理、力学性能。实验结果表明：粉末冶金工艺制备的合金硼元素分布均匀、而铸造合金硼元素偏聚在晶界,所以前者制备的合金塑性明显优于后者。检测了304B7高硼钢的线膨胀系数和热导率,与普通304不锈钢性能无明显区别。     

镍基高温合金GH4151的偏析及相析出行为

摘要：利用电子探针(EPMA)、场发射扫描电镜（SEM）及差热分析（DTA）研究了GH4151合金的元素偏析行为、铸态组织特征以及析出相种类,并对合金凝固过程进行讨论。结果表明：GH4151合金凝固过程中,W元素偏聚于枝晶干,Mo、Nb、Ti元素偏聚于枝晶间,Co、Cr、Al元素几乎不发生偏析,Nb、Ti元素偏析较重。GH4151铸锭心部为粗大的等轴晶,主要析出相包括强化相γ′相、一次碳化物、η相、（γ+γ′）共晶相以及Laves相,其中枝晶间分布的η相、（γ+γ′）共晶相和Laves相为低温脆性相在凝固末期形成,扩大了合金的凝固区间,从而导致合金热裂敏感性增加。     

NaCl+HCl溶液中Ce对双相不锈钢腐蚀行为的影响

为了研究酸性NaCl溶液中双相不锈钢的耐腐蚀性能,以含微量稀土Ce的UNS S31803双相不锈钢为研究对象,采用电化学阳极极化和交流阻抗相结合的方法测试其在NaCl+HCl混合溶液中的耐腐蚀性能。利用扫描电镜(SEM)观测腐蚀后的形貌特征,采用电子探针(EPMA)检测合金元素与杂质元素的分布特征,分析Ce元素的加入对双相不锈钢电化学腐蚀行为的影响机制。结果表明,钢中存在两相的选择性腐蚀并伴有局部点蚀,其中铁素体相是腐蚀较严重的相;阳极极化测试与交流阻抗测试结果相吻合,Ce拓宽了试验钢的钝化区间;Ce通过净化钢液、降低S和P元素在相界的偏聚及使Cr、Ni和Mo等合金元素在两相中的分布更均匀等作用,提高了钢的耐腐蚀性能。     

Al-Er合金中Al3Er相的形成及演化

采用金属型水冷模铸造制备了不同含铒量的Al-Er二元合金,通过对铸态及均匀化处理后实验合金的金相观察、电子探针(EPMA)以及透射电镜分析,研究了对不同含量的Er在AI-Er合金中的存在形式及固溶Er在纯铝中的固溶度.结果表明,在本实验条件下铒元素以过饱和固溶体形式存在于α-Al中和以Al3Er化合物的形式分布在晶界上,另外Er在铝基体的最大固溶度为O.1%(质量分数).     

挤压铸造零件沿流程方向的成分偏析及组织偏聚

采用挤压铸造(液态模锻)工艺制备了A357铝合金螺旋线试件,使用化学成分分析和金相分析方法研究了流程长度对合金成分偏析及组织偏聚的影响.结果表明:在沿流程方向上,流程的开始端和流程末端的Si元素和Mg元素含量大于流程中段的含量.合金的初始α晶粒尺寸随着流程长度的增加先增大后变小.初生固相率随着流程长度的增大呈现波动变化.造成流程成分偏析和组织变化的原因是在挤压铸造凝固阶段中补缩液相的强迫运动.      

Re和Cr变化对定向高温合金凝固和偏析的影响

采用真空熔炼和定向凝固技术制备不同Re和Cr含量的定向试棒.利用差热分析(DSC)研究不同Re和Cr含量定向凝固高温合金的凝固行为,利用扫描电镜(SEM)和电子探针(EPMA)研究合金组织和元素分布特征.研究发现Re含量的增加对合金的固/液相线温度影响不大,Cr含量的增加降低了合金的固/液相线温度;随着Re含量增加,加...     

微量杂质在工业纯钛中的存在形式及其对力学性能的影响

采用差示扫描量热法(DSC)、X射线衍射(XRD)、扫描电镜及其附带的能谱仪(SEM+EDS)、电子探针(EPMA)等分析方法和力学性能测试,研究常温下铁、硅、氯、氮、氧、碳(Fe,Si,Cl,M,O,C)等杂质在工业纯钛中的存在形式、分布状况及其对力学性能的影响。结果表明:在工业纯钛中,铁、硅、氯杂质元素的微区元素浓度较低,只有极少区域存在偏聚;碳元素分布不均匀,微区偏聚现象明显;氧元素在工业纯钛中含量较少且分布均匀;随铁、氮、氧、碳、氯等杂质含量增加,工业纯钛的强度和硬度大幅提高,塑韧性显著降低,最大硬度HB增幅为24,屈服强度和抗拉强度的最大增加幅度分别为144 MPa和122 MPa,伸长率的减幅最大为19.8%。     

垂直半连续铸造Cu-15Ni-8Sn合金组织及性能研究

采用垂直半连续铸造法制备Cu-15Ni-8Sn合金,并对合金的凝固组织、元素偏析以及热处理后的组织和性能进行了分析。采用普通熔铸法制备Cu-15Ni-8Sn合金的铸态组织主要由贫Sn的α-Cu(Ni, Sn)固溶体、富Sn的γ相以及片层状的（α+γ）组成,并且Sn元素主要偏聚在晶界上。在垂直半连续铸造的过程中同时施加机械振动和电磁场具有明显的晶粒细化效果,同时有效减轻了Sn元素的宏观反偏析和微观晶界偏析,富Sn相比较均匀地分布在晶粒内部和晶界上。Cu-15Ni-8Sn合金经过850℃固溶、 90%轧制和400℃时效1 h后可获得最佳的综合性能,此时合金的硬度为HV 401,导电率为8.4%IACS,抗拉强度为1233 MPa,屈服强度为1185 MPa,伸长率为4.5%。     

钢中元素偏聚的研究现状及其发展趋势

 固溶状态下,钢中合金元素会在晶界、缺陷等处优先出现偏聚现象,对钢材的组织和性能产生显著影响。由于元素在钢中的偏聚量小,不易观察,而且影响偏聚的因素很多,导致钢中元素偏聚的理论研究进展缓慢。为了揭示不同元素在钢中的偏聚机理,充分发挥钢中元素偏聚的积极作用,从偏聚类型出发,总结分析了元素偏聚的影响因素和控制手段,重点介绍了几种常见元素的偏聚现象,深入分析其偏聚量及位置对钢材性能的影响,同时还介绍了几种观察元素偏聚的手段。期望能为揭示钢中偏聚行为、发挥其作用提供参考,也为后续偏聚行为的研究提供一些参考。     

微量Mg在GH99合金中分布形态的研究

GH99合金中加入适量Mg，可使900℃的持久强度明显提高。应用JCXA-733电子探针研究微量元素Mg在GH99合金中的分布规律及对夹杂物分布状态的影响，Mg偏聚于一次碳化物MC相界处并固溶于MC相内，并使棱角规则或长条状一次MC明显钝化。随着合金中Mg含量的增加，晶界处的MC数量明显减少。Mg亦偏聚在晶界处，起到净化晶界，分割晶界碳化物的作用。使晶界上二次碳化物均匀呈链状分布。晶界处Mg的含量随合金中Mg含量的增加而增加。     

Phase precipitation and segregation behavior of nickel based superalloy GH4151

The element segregation behavior, as cast microstructure characteristics and precipitation phase types of GH4151 alloy were studied by electron probe microanalysis (EPMA), field emission scanning electron microscopy (SEM) and differential thermal analysis (DTA), and the solidification process of the alloy was discussed. During the solidification of GH4151 alloy, element W is segregated to the dendrite cores, elements Mo, Nb and Ti are segregated to the interdendritic regions, and elements Co, Cr, Al are not segregated, elements Nb and Ti are biased more heavily. The core of GH4151 ingot is coarse equiaxed grains, whose main precipitated phases include γ′, MC carbide, η phase, (γ+γ′) eutectic phase and Laves phase. At the end of solidification, low temperature brittle phases such as η phase, (γ+γ′) eutectic phase and Laves phase are formed, which enlarge the solidification range and increase the hot cracking sensitivity of the alloy.     

热浸镀锌铝镁镀层微观组织试验

 研究了热浸镀工艺对于镀层的微观结构的影响,利用扫描电镜（SEM）及能谱分析（EDX）观察了Zn-Al-Mg镀层表面以及截面的微观结构、合金层的形貌、镀层中各相的成分组成,利用辉光放电发射光谱仪(GDS)分析了镀层中各元素沿深度方向的分布,利用电子探针（EPMA）分析了镀层中各元素的分布,利用X射线光电子能谱（XPS）分析了镀层表面元素,利用X射线衍射(XRD)分析了镀层的相组成。结果表明,镀层中各元素沿镀层的深度方向的分布并不均匀,Mg在镀层表面富集,镀层组织呈现多相混合结构,以Zn晶粒、MgZn2与Zn组成的共晶为主,同时存在块状富铝相以及一层较薄的合金层。     

Effect of vanadium on grain boundary segregation of phosphorus in low alloy steels

The phosphorus grain boundary segregation at 853 K was investigated in three low alloy steels with different vanadium content. Kinetic dependence of the phosphorus grain boundary concentration was determined experimentally by means of AES and described theoretically, as well. To assess the influence of the individual alloying elements on the phosphorus segregation, the metal composition of carbide phases at 853 K was predicted by means of thermodynamic calculations and confirmed by experimental measurements (TEM + EDX). The vanadium was found to enhance the phosphorus grain boundary segregation by reducing the amount of dissolved and segregated carbon. Thereby, the equilibrium of mutual displacement C (segregated) ? P (segregated) was shifted to more phosphorus segregation. The results achieved indicate that vanadium indirectly increases sensitivity of low alloy steels to intergranular embrittlement.     

一种合金焊丝模铸锭中心孔洞的成因和措施

高强度合金焊丝钢广泛用于工程机械行业,具有残余元素低、纯净度高的特点,氢、氧、氮气体元素含量均要求严格,国内该系列焊丝材料主要依赖进口。为了进一步开拓系列高端焊丝钢市场,开发了新型高强度合金焊丝钢。生产过程发现模铸钢锭轧制后探伤不合格,取样发现初轧坯横截面低倍中心出现孔洞缺陷,影响材料质量。通过低倍试验和EPMA分析结合材料成分采用Thermo-Calc软件计算固液相线,分析发现钢种固液线差值相对较小是导致钢锭中心孔洞的主要原因。采用优化钢液浇注过热度和模铸浇注时补缩控制,避免了钢锭中心孔洞缺陷的产生。     

The Oxidation behavior of an iron-chromium alloy containing yttrium or rare earth elements between 900° and 1200°C

The oxidation behavior of an Iron-15 wt pct Chromium alloy, some containing small additions of yttrium or rare earth elements, have been observed using a TG and an EPMA method at temperatures between 900° and 1200°C. Yttrium or rare earth element additions to the Iron-Chromium alloy result in a rapid initial oxidation rate, but decrease the total weight gain of the Iron-Chromium alloy at the final time of exposure. The line trace obtained indicates that the increased segregation of chromium content in the inner oxide layer of the alloy containing yttrium or rare earth elements and also shows that the enriched concentration of yttrium or lanthanum is detected within the chromium oxides which exist near the oxide scale/alloy matrix interface. Yttrium or rare earth element oxides serve as the sites for the protective chromium oxide scales.     

Modeling of Solutionizing and Solute Redistribution in a Co-Cast Bi-Layer Al Alloy System

The effect of high-temperature treatment on solutionizing and solute diffusion in a co-cast X609-AA3003 alloy system is examined via a coupled dissolution and diffusion model using finite-element analysis. The model describes the kinetics of the dissolution of intermetallic particles of Mg₂Si and Si along with the diffusion of alloying elements of Mg, Si, and Cu across the interface between the two alloy layers. The results are verified using electron probe microanalysis (EPMA) measurements.     

Microstructure of Fe-Based Alloy Hardfacing Coating Reinforced by TiC-VC Particles

Mierostrueture of the Fe-based alloy hardfaeing coating reinforced by TiC-VC particles was investigated by means of SEM, TEM, XRD and EPMA. The thermodynamics and effect of elements on the carbides were discussed. The result shows that TiC-VC carbides can be formed during arc welding. Carbides with particle size of 2 ～4μm are uniformly dispersed in the matrix. Evidently the covering components and their amount affect the microstrueture and hardness of the coatings. An excellent microstructure and hardness of hardfacing coating were obtained, while the amount of graphite, FeTi and FeV was controlled within the range of 8%- 10%, 15%- 18% and 8%- 12%, respectively.     

铝与K2TiF6混合粉末的高能球磨反应

以Al粉和K2 TiF6 混合粉末为原料 ,利用高能球磨法制备Ti Al基金属间化合物。采用XRD ,SEM ,EPMA和DTA等方法对球磨 1,2 5 ,5 ,8h的粉末进行分析 ,在球磨时间超过 2 .5h的粉末中有TiAl3,TiAl出现 ,并伴有副产物KAlF4 和K3AlF6 生成。随着反应的进行 ,产物中TiAl相含量逐渐增加 ,产物粒度可达纳米级。     

Hydrogen embrittlement of iron-nickel alloys

The effects of hydrogen on the deformation and fracture of alloys in the Fe−Ni alloy system were studied as a function of the alloy composition and the amount of sulfur segregated at the grain boundaries. A ductile-to-brittle transition in the tensile parameters and in the fracture mode was observed as the hydrogen fugacity was increased. The variation of this transition fugacity with segregated sulfur and with the alloy concentration was studied.