材料期刊网

LOW CYCLE FATIGUE BEHAVIOR OF AZ91HP ALLOY IN AS HIGH PRESSURE DIE CASTING

Z. Liu , Y. Y. Xu , Z.G. Wang , Y. Wang , and Z. Y. Liu State Key Laboratory for Fatigue and Fracture of Materials , Institute of Metal Research , Tile Chinese Academy of Sciences , Shenyang 110015 , China School of Material Science and Engineering , Shenyang Technical University , Shenyang 110023 , China

金属学报(英文版)

Fully reversed total strain-controlled low-cycle fatigue tests were conducted at room temperature in air to study fatigue behavior of AZ91HP in as high pressure die casting and subsequently heat treatments. All the specimens in different heat histories exhibited cyclic strum hardening in different degrees. It was difficult to distinguish the fatigue behaviors of the die-casting specimens from the solution-aging specimens. However the solution treated specimens showed longerfatigue life at high strum amplitude and shorter fatigue life at low strain amplitude than die-casting and the solution-aging specimens though they had the lowest yield strength with higher strain hardening. Fatigue fracture surfaces for strain amplitude larger than 0.005 showed very similar to those of the monotonic tensile tests. The SEM examination revealed that regions of fatigue crack growth and final fracture could be characterized by quasi-cleavage mech anisms, but some shallow dimples, slip bands and secondary cracks were found on the fracture surface in the fracturs crack growth areas.

关键词: low-cycle fatigue , null , null , null

Improving glass-forming ability of Mg-Cu-Y via substitutional alloying: Effects of Ag versus Ni

Journal of Materials Research

Based on the best bulk metallic glass (BMG) forming alloy in the Mg-Cu-Y ternary system, we introduced Ag (or Ni) to partially substitute for Cu to improve the glass-forming ability (GFA). The objective of this paper is twofold. First, we illustrate in detail a recently developed search strategy, which was proposed but only briefly outlined in our previous publication [H. Ma, L.L. Shi, J. Xu, Y. Li, and E. Ma: Discovering inch-diameter metallic glasses in three-dimensional composition space. Appl. Phys. Lett. 87, 181915 (2005)]. The protocol to navigate in three-dimensional composition space to land large BMGs is spelled out step-by-step using the pseudo-ternary Mg-(Cu,Ag)-Y as the model system. Second, our ability to locate the best BMG former in the composition tetrahedron allows us to systematically examine, and conclude on, the effects of a given alloying element. The large improvement in glass-forming ability in the Mg-(Cu,Ag)-Y system relative to the based ternary will be contrasted with the reduced glass-forming ability in the Mg-(Cu,Ni)-Y pseudo ternary system. It is demonstrated that the improvement of glass-forming ability requires judicious choice of substitutional alloying elements and concentrations, rather than simple additions of multiple elements assuming the "confusion principle."

关键词: bulk metallic-glass;shaped copper mold;amorphous-alloys;thermal-stability;ternary-system;casting method;p system;diameter;zr;mm

稀土Y对镁合金显微组织及腐蚀性能的影响

马宏 , 彭晓东 , 谢卫东

腐蚀学报（英文）

利用对掺法熔铸镁合金AJ61+xY, 研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为. 结果表明, 添加稀土Y使AJ61镁合金的晶粒明显细化,Mg₁₇Al₁₂ 相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al₂Y、Al₃Y, AJ61镁合金的耐腐蚀性得到明显改善. 耐腐蚀性顺序为:AJ61+1.5%Y>AJ61+2.0%Y>AJ61+1.0%Y>AJ61+0.5%Y.

关键词: Mg-6Al-1Sr 镁合金 , yttrium , microstructure , corrosion resistance

稀土Y对镁合金显微组织及腐蚀性能的影响

马宏 , 彭晓东 , 谢卫东

腐蚀学报（英文）

利用对掺法熔铸镁合金AJ61++xY,研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为.结果表明,添加稀土Y使AJ61镁合金的晶粒明显细化,Mg17Al12相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al2Y、Al3Y,AJ61镁合金的耐腐蚀性得到明显改善.耐腐蚀性顺序为:AJ61+1.5%Y＞AJ61+2.0%Y＞AJ61+1.0%Y＞AJ61+0.5%Y.

关键词: Mg-6Al-1Sr镁合金 , 钇 , 显微组织 , 耐腐蚀

Corrosion of Y, Fe and Fe-15Y in H_2-H_2S Mixture under 10~(-3) Pa S_2 at 600～800℃

Yan NIU , Weitao WU and Chaoliu ZENG (State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)F. Gesmundo and F. Viani (Instituto di Chimica , Facolta di Ingegneria , Un

材料科学技术（英文）

The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe

关键词:

Roles of Zr and Y in cast microstructure of M951 nickel-based superalloy

Transactions of Nonferrous Metals Society of China

The influence of Zr and Y on the cast microstructure of a nickel-based superalloy was investigated by optical microscopy (OM), scanning electron microscopy(SEM), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD). The gamma+gamma' eutectic volume in the superalloy rises notably with the increase of Zr or Y content. Meanwhile, the morphologies of primary MC carbides change from needle and platelet-like to blocky shape with increasing Zr and Y doped. The XRD results show that the primary MC carbide lattice constant increases with Zr and Y additions, and EPMA investigation shows that the platelet-like MC carbides contain primarily Nb and C, while those carbides in blocky shape have 39.2% Zr and 39.6% Nb in average,. These influences on the cast microstructure can be attributed to the atomic size effects of Zr and Y.

关键词: yttrium;zirconium;carbides;nickel based superalloys;microstructure;solidification;carbide morphology;mechanical-properties;boron;ni3al;yttrium;sulfur

Corrosion of Y, Fe and Fe-15Y in H-2-H2S mixture under 10(-3) Pa S-2 at 600 similar to 800 degrees C

材料科学技术（英文）

The corrosion of an Fe-based alloy containing 15 wt pet Y in H-2-H2S mixtures under 10(-3) Pa S-2 was studied at 600 similar to 800 degrees C in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneficial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus, Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition, but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12 similar to 17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe.

关键词: high-temperature sulfidation;most-reactive component;ni-nb alloys;h2-h2s mixtures;behavior;600-degrees-c-800-degrees-c;oxidation

离子注入Y对Fe3Al高温氧化行为的影响

王永刚 , 何业东 , 朱日彰

中国稀土学报

通过金属蒸汽真空弧离子源(简称MEVVA)方法在Fe3Al表面离子注入Y.在1000°空气中的氧化实验表明,Fe3Al经离子注入Y后,初期氧化速率略有升高,但稳态氧化速率大大降低,氧化膜的塑性和粘附性大大提高,抗氧化性能明显改善.其原因在于注入的Y+在氧化过程中优先氧化,阻碍金属离子向外扩散,促进氧向内传输,改变了氧化膜的形成和生长机制.

关键词: 稀土 , 钇 , Fe3Al , 离子注入 , 高温氧化行为

Laser surface cladding of ZM5 Mg-base alloy with Al+Y powder

Transactions of Nonferrous Metals Society of China

The surface properties of ZM5 Mg-base alloy were modified by laser cladding with Al+Y powder. Laser cladding was carried out with a 5 kW continuous wave CO2 laser by melting the preplaced powder mixture of Al and Y. Following laser cladding, the cladding zone was characterized by a detailed microstructural observation and phase analysis. Moreover, the microhardness and element distribution were evaluated in detail. The surface modified layer consists of Mg-17 Al-12 and Al-4 MgY phases, while alpha-Mg and Mg-17 Al-12 in the substrate. The microhardness of the cladding zone was significantly enhanced as high as HV122 - 180 as compared to HV60 - 80 of the substrate region. The maximal hardness about HV224 is in the interface due to the formation of intermetallic Mg-17 Al-12 phase. The microstructure is refined and Mg diffuses into the cladding material which leads to the formation of Mg-17 Al-12.

关键词: laser cladding;ZM5 Mg base alloy;rare earth;Al plus Y powder;microstructure;magnesium;microstructures;behavior

ELECTRONIC STRUCTURE OF Pd-Y-Si GLASSES

LUO Meiqing CHEN Nianyi Shanghai Institute of Metallurgy , Academia Sinica , Shanghai , ChinaYU Zhizhong Shanghai Institute of Testing Technics , Shanghai , ChianNING Yuantao ZHOU Xinming Kunming Institute of Precious Metals , Kunming , China CHEN Nianyi , Professor , Shanghai Institute of Metallurgy , Academia Sinica , Shanghai 200050 , China

金属学报(英文版)

The electronic structure of Pd-Y-Si glass has been investigated by ESCA and quantum chem- ical calculation.It was found that the valence electrons of Y transferred to Si atoms in this metallic glass,forming polar covalent bonds.Perhaps these strong covalent bonds link Si and Y atoms to form clusters that hinder the process of crystallization.

关键词: Pd-Y-Si glass , null , null , null