钇添加量和固溶处理对AZ91D镁合金组织的影响

添加适量稀土元素钇的AZ91D镁合金采用真空熔炼、金属型铸造的方法获得,并对之进行了固溶处理;研究了钇的添加量及固溶处理时间对AZ91D合金组织的影响.结果表明,经350℃固溶处理16h、钇含量约为0.6％的AZ91D镁合金具有均匀、细小的组织和最佳的力学性能和.     

稀土Y对AZ61镁合金微观组织和力学性能的影响

研究了稀土钇含量对AZ61镁合金显微组织和室温及高温力学性能的影响。实验结果表明：加入稀土钇可使AZ61合金铸态组织中的β相数量减少、铸态晶粒细化;大部分钇与铝结合生成高熔点、高热稳定性的稀土相A12Y3;固溶处理后,β相完全溶解而稀土相则以块状或杆状存在于晶界周围;适量的稀土钇可以提高AZ61合金的室温及高温强度、硬度和延伸率;而过量的稀土钇则会导致AZ61合金的性能下降;稀土钇的含量为1．0％时合金可得到较佳的力学性能。     

微量元素对钛硅共晶合金压缩性能的改善

研究了钇、铍、钐、硼、钕等微量元素对Ti-8.5%Si(质量分数)共晶合金微观组织和室温压缩性能的影响。试验表明,添加适量钇、铍、钐、硼、钕等元素,均可有效提高Ti-8.5%Si合金的室温压缩强度和塑性,并细化其微观组织。其中,硼对Ti-8.5%Si合金室温压缩塑性的改善最为显著。分析认为,硼很可能以异质形核质点的形式,提高合金的形核率,从而细化合金的微观组织,改善合金的室温塑性。     

钇对Ti-23Al-25Nb合金热处理组织及性能的影响

采用DTA分析Ti-23Al-25Nb合金和Ti-23Al-25Nb-0.36Y合金的相变特征,并根据DTA曲线特征制定热处理工艺,用SEM,XRD分析热处理后合金试样的显微组织及相组成,用TEM分析原始组织中钇的存在形式,用Instron-5569万能材料试验机进行室温压缩试验.结果表明,钇在原始组织中以Y2O3形式存在;钇没有改变Ti-23Al-25Nb合金的相变温度;加入钇后,在1320℃淬火,B2相晶粒比较粗大,随着淬火温度的降低,O相增加,并且O相板条变细而杂乱,有利于提高合金的塑性和抗蠕变性能;加入钇后,合金强度提高,原因是第二相粒子Y2O3弥散强化的结果.     

稀土钇对银合金组织和性能的影响

采用X-射线衍射、金相和硬度分析方法,考察了铝和微量稀土钇对925银合金的组织和性能的影响,并对材料的硫化腐蚀性能进行了研究.结果表明:稀土钇在银合金中主要以固溶的形式存在.添加质量分数为0.037%钇的银合金晶粒最细,合金硬度值最高,其抗硫化性能与不含钇的合金相当.     

钇基稀土对铸造Ni基合金的组织和性能的影响

本文试验研究了钇基稀土用于改善铸造镍基耐蚀合金性能的效果。结果表明,添加适量的稀土可以明显地细化合金的晶粒,改变碳化物的形态和分布,阻止碳化物的集聚,改变夹杂物的性质,并使其总量减少、变小、球化和弥散分布,从而使合金的耐蚀性能和力学性能得到提高,使其切削加工性能得到改善。     

稀土钇对铸造Al-Cu-Mg-Ag合金组织和力学性能的影响

通过拉伸试验、金相观察、扫描电子显微分析及透射电子显微分析等方法,研究了稀土钇对铸造Al-Cu-Mg-Ag合金组织和力学性能的影响,揭示了合金微观组织和力学性能之间的联系.结果 表明:添加w(Y)=0.3％的稀土钇显著改善了该合金的室温塑性,但对合金屈服强度影响不大.定量计算结果显示,在欠时效态的Al-Cu-Mg-Ag...     

稀土钇对AZ80镁合金微观组织和性能的影响

采用扫描电镜(SEM),金相显微镜(OM),X射线衍射(XRD),拉伸试验及腐蚀失重等测试手段对添加不同含量稀土钇对AZ80镁合金微观组织和性能的影响进行了研究。结果表明,适量钇的添加使得AZ80镁合金的组织得到细化,β-Mg17 Al12相的数量显著下降,并且由连续网状分布变为断续、均匀分布,同时生成新的稀土相Al2Y。添加0.5%Y时,合金室温下抗拉强度达到199.286 MPa,伸长率为6.155%,分别增加了7.49%,7.98%,腐蚀速率为0.2585 mg.cm-2.d-1,仅为原始合金的48.07%,表现较好的综合性能。     

稀土元素钇对72.5Cu-22.7Zn-3.4Al黄铜组织性能的影响

研究少量稀土元素钇(0.01%、0.03%、0.05%)对铝黄铜(72.5Cu-22.7Zn-3.4Al)合金在铸态、热轧态、退火态及冷轧态的组织及性能的影响.结果表明,钇能明显改变铸态α相晶粒形状及尺寸,随合金中钇含量的增加,α相晶粒的尺寸减小,形状更趋于针状,β相分布更均匀;合金的抗拉强度、伸长率及硬度提高.铝黄铜中添加0.03%的钇及合理的生产工艺生产的0.25 mm厚的带材,其抗拉强度达745.9 Mpa、伸长率为2.1%、硬度为87.7HRB.     

稀土元素对LC4合金组织与性能的影响

本文通过组织检验和性能测试,研究了稀土元素钇和铈对LC4合金的组织与性能的影响。试验结果表明:合金中含有0.02～0.2％铈对力学性能和腐蚀性能影响不大。合金中含有微量钇时,降低力学性能;当合金中含有0.2％左右钇时,能显著地提高合金淬火过烧温度和抗应力腐蚀性能。     

Y含量对Mg-Zn-Y合金组织和性能的影响

采用X射线衍射和金相显微分析研究了元素Y对Mg-3Zn-xY（x=0．5、1．5、3．0．6．0，质量分数／％）合金显微组织和力学性能的影响。结果表明，在基体中和晶界分布的弥散质点随Y含量的增加而增多，尺寸增大。合金中二次相的种类取决于加（Zn）／w（Y）之比值，随着Y含量的增加，合金中的二次相依次从Mg，Zn，相＋I相、I相＋W相到W相＋H相、H相转变，晶间组织的形态也由点状、细线状向网状转变。合金的抗拉强度、硬度、冲击韧度随着Y含量的增加而提高，塑性则逐渐下降。但Y含量达到6％时合金的综合力学性能下降。     

FRACTURE MECHANISM IN Ti_3Al Si Nb ALLOYS

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Effects of minor yttrium addition on hot deformability of lamellar Ti-45Al-SNb alloy

The effects of 0.3%（molar fraction, the same below） yttrium addition on hot deformability of lamellar Ti-45Al-5Nb alloy were investigated by simulated isothermal forging tests. The ingots with the nominal compositions of Ti-45Al-5Nb and Ti-45Al-5Nb-0.3Y were prepared by induction skull melting. Simulated isothermal forging tests were conducted on Gleeble 1500D thermo-simulation machine using a 6 mm in diameter and 10 mm in length compressive specimen at the deformation temperatures of 1 100, 1 150, 1 200 ℃ and strain rates of 1.0, 0.1, 0.01 s^-1. The results show that yttrium addition remarkably improves hot deformability of Ti-45Al-5Nb alloy. An appropriate hot deformation processing parameter of Ti-45Al-5Nb-0.3Y alloy is determined as 1 200 ℃, 0.01 s^-1. The flow stresses are decreased by yttrium addition under the same compressive conditions. The activation energies of deformation Q are calculated as 448.6 and 399.5 kJ/mol for Y-free and Y-containing alloys, respectively. The deformed microstructure observation under 1 200 ℃, 0.01 s^-1 condition indicates that Ti-45Al-5Nb-0.3Y alloy shows more dynamic recrystallization. The improvement of hot deformability of Ti-45Al-5Nb-0.3Y alloy induced by yttrium addition should be attributed to that the smaller the original lamellar colonies, the lower the deformation resistance and activation energy of deformation are, and the more the dynamic recrystallization is.     

Y对TiAl合金显微组织及性能的影响

系统地研究了Ti-47Al-xY系[x（摩尔分数／％）分别为0、0．1、0．3、0．5、0．7、1．0]合金的显微组织及室温力学性能。结果发现：随着Y含量的增加，合金由柱状晶转变为等轴晶（x≥0．3），而且合金的晶粒尺寸和层片间距随着Y含量的增加而降低；当Y含量高于0．1％时，晶内弥散分布细小YAl2相颗粒的同时，YAl2相开始在晶界处偏析，且随着Y含量的增加，晶界偏析越来越严重；当Y含量达到1．0％时，晶界处YAl2相闭合成网络状。拉伸测试表明，Y含量为0．3％～0．5％的Ti-47Al合金有较高的强度和塑性。分析得知，YAl2相的尺寸及分布对性能起着重要的作用。一方面，组织的细化和晶内细小的YAl2相有利于性能的改善，另一方面，晶界处富集的大尺寸YAl2相显著恶化TiAl合金的性能，特别是在Y含量高于0．5％的TiAl合金中。     

Effect of Yttrium as Alloying Element on a Model Alumina-Forming Alloy Oxidation at 1100 °C

In order to study the effect of yttrium as alloying element on the high-temperature oxidation of an alumina-forming alloy, 0.093 wt% yttrium was incorporated into a model FeCrAl alloy. Yttrium has a beneficial effect on the isothermal oxidation behavior in air at 1100 °C. Glancing angle X-ray diffraction made on a sample oxidized for 1000 h under thermal cycling conditions indicated that yttrium is located at the internal interface as Y₃Al₅O₁₂. Secondary neutral mass spectrometry results showed that the diffusion mechanism is modified by the presence of yttrium as an alloying element. Moreover, the beneficial effect of yttrium on the alloy oxidation is also related to a reduced metallic grain size. The growth of metal grains during oxidation was especially observed on the yttrium-free FeCrAl alloy. It is also well established that the diffusion mechanism in the oxide scale is modified by yttrium. The aim of the present work was to show that yttrium also plays a role on the aluminum diffusion in the metallic substrate and has a strong influence on the kinetic transient stage during the FeCrAl–0.1Y oxidation.     

稀土元素和Ti对ZM5镁合金组织和性能的影响

用金相显微镜、X射线衍射仪分析了添加稀土元素Y、Nd和钛中间合金的Mg-8．5Al-0．5Zn（ZM5）合金的组织和相组成,测试了合金的室温力学性能。结果表明,添加稀土元素Y、Nd的ZM5镁合金中出现了新的镁．稀土相MgY、Mg12Nd,而在同时添加稀土元素Y、Nd和钛中间合金的合金中,还出现了新相Ti2Mg3Al18;添加稀土元素Y、Nd的ZM5镁合金在拉伸性能、硬度以及组织都明显优于ZM5镁合金,而同时添加稀土元素和Ti合金的镁合金其性能又显著优于单独添加Y或Nd的合金。     

Fe-Y合金在800℃空气中的氧化行为

研究了Fe-5Y和Fe-10Y合金在800℃空气中的氧化行为。结果表明：二元Fe-Y合金氧化动力学曲线不规则,此温度下Fe-10Y合金的氧化速率高于Fe-5Y合金的氧化速率。Fe-5Y合金及Fe-10Y合金形成了相似的氧化膜结构,且它们都发生了内氧化现象。同时合金未形成单一的Y₂O₃层,这归结于Y在Fe中非常低的溶解度及合金中两相共存而阻碍了Y通过合金向外扩散。     

Effect of yttrium on microstructure and properties of Ni3Al base alloy IC6

The effect of yttrium on the microstructure of alloy IC6 was examined by scanning electron microscopy (SEM), the energy dispersive spectrum (EDS) technique of electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The results show that the microstructure of alloy IC6 with addition of 0.04–0.12 wt% yttrium has no obvious difference compared with that of the alloy without yttrium, and that Ni₃Y and Mo_1.24Ni_0.76 precipitate in the interdendritic area surrounded by large size γ′ phase in the alloy with addition of 0.20–0.30 wt% yttrium. The effect of yttrium on high temperature static and cyclic oxidation resistance, stress rupture properties and thermal fatigue resistance was also investigated in this study.     

Influence of the mode of introduction of a reactive element on the high temperature oxidation behavior of an alumina‐forming alloy. Part III: The use of two stage oxidation experiments and in situ X‐ray diffraction to understand the oxidation mechanisms

The aim of this work was to investigate several different yttrium introduction routes to improve the high temperature oxidation resistance of a Fe‐20Cr‐5Al model alloy. Y₂O₃ sol‐gel coatings, Y₂O₃ metal‐organic chemical vapor deposition (MOCVD) coatings, yttrium ion implantation and yttrium as alloying element (0.1 wt.%) were the different methods of introduction of the reactive element. Both isothermal and cyclic oxidation tests showed that the surface introduction of yttrium or yttrium oxide did not drastically improve the oxidation behavior of the steel. Complementary experiments were performed to understand the lack of major beneficial effects of the so‐treated samples. Two stage oxidation experiments under 200 mbar ¹⁶O₂ and ¹⁸O₂ followed by secondary neutral mass spectrometry (SNMS) were performed to understand the alumina scale growth mechanisms, according to the introduction route of the reactive element. The results exhibited that the yttrium induced an increase of the inward transport of oxygen through the alumina scale compared to the untreated specimen. Nevertheless, the outward transport of aluminum was generally observed, except for the specimen containing Y as alloying element, which exhibited only a single¹⁸O peak close to the metal/oxide interface. Phase transformations during the oxidation at 1100°C were registered by in‐situ X‐ray diffraction (XRD). The untreated alloy was only covered by a thin layer of α‐Al₂O₃. For implanted specimens, yttrium was incorporated in Y₃Al₅O₁₂ and YAlO₃ phases. All the YAlO₃ is transformed into Y₃Al₅O₁₂ after less than 10 h. For the MOCVD or the sol‐gel coated samples, the primary formed YAlO₃ phase was progressively transformed into Y₃Al₅O₁₂. For the Fe‐20Cr‐5Al‐0.1Y alloy, no yttrium containing phases could be detected, even after 40 h of oxidation test at 1100°C.     

Effect of Yttrium on Microstructure and Properties of High Temperature Alloys

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