Influence of Fe on Microstructure and Mechanical Properties in Pdoped Ni–Cr–Fe Alloys

The influence of Fe on the microstructure and mechanical properties of P-doped Ni–Cr–Fe alloys has been investigated.Results showed that increasing Fe content refined the dendrite microstructure and enhanced the solubility of P in as-cast alloys. The change of microhardness in different dendrite regions was attributed to the segregation of P atoms in solid solution state, which had strengthening effects. Increasing Fe contents from 15.2 to 60.7 wt% reduced the yield strength and tensile strength but had little influence on the elongation of alloys. The stress rupture life of alloys after heat treatment decreased with the increment of Fe contents, and the failure fracture modes transferred from transgranular to intergranular fracture mode. The change of fracture modes was due to the weakness of grain boundaries caused by the increment of Fe.In addition, the precipitation of M_(23)C_6 was believed to be related to the segregation of P toward grain boundaries, which led to the fluctuation of carbon and chromium atoms near the grain boundaries in alloys with low Fe contents. Consequently, the increment of Fe decreased the strength of matrix and changed the existence of P atoms and the precipitates at grain boundaries.     

Effect of Ag on the Microstructure,Mechanical and Bio-corrosion Properties of Fe–30Mn Alloy

In the current work, biodegradable Fe–30 Mn– X Ag( X = 1, 2, 5, 10 wt%) alloys were prepared by the rapid solidifi cation with copper-mold-casting technology. Phase analysis demonstrates that Fe–30 Mn– X Ag alloys consist of austenite γ phase with a fcc structure and martensite ε phase with a hcp structure. The yield strength of the samples increases with increasing Ag contents. Compared with Fe–30 Mn alloy, the degradation rates of Fe–30 Mn– X Ag in Hank's solution are signifi cantly improved. Cytotoxicity evaluation reveals that the Fe–30 Mn–1 Ag and Fe–30 Mn–2 Ag alloys perform less toxicity on the Human Umbilical Vein Endothelial Cells(HUVEC), while Fe–30 Mn–5 Ag and Fe–30 Mn–10 Ag alloys perform no toxicity on it. The contact angles of deionized water on the Fe–30 Mn– X Ag alloy surface were ranged from 55° to 69°, which is benefi cial to the adhesion and growth of the cells. Besides, the addition of Ag leads to a much lower M/H slope, particularly for the Fe–30 Mn–5 Ag alloy exhibiting a non-magnetic property as SS316 L. Therefore, the present Fe–30 Mn– X Ag alloys would be potential candidates for degradable metals.     

Effect of the Application of a Mechanical Load on the Oxide-Layer Microstructure and on the Oxidation Mechanism of Ni–20Cr Foils

The effect of a tensile load on the oxidation kinetics and mechanism ofNi–20Cr was studied by comparison of the oxidation behavior ofNi–20Cr thin strips in air under classical conditions, i.e., withoutany applied mechanical load and under tensile creep, at temperatures between500 and 900°C. The study was performed mainly by comparisons of crosssections of oxidized samples observed by SEM. The results obtained clearlyindicate that applying a tensile load induces an increase in the oxidationrate, does not modify the oxide-film morphology, but promotes the formationof internal oxidation at low temperatures, 500–600°C, and notablyincreases the thickness of the intermediate NiCr₂O₄layer at 900°C. This is related to the acceleration of anionic diffusionwhen a tensile load is applied, due to the formation of fast-diffusion byshort-circuit paths.     

Effect of Strontium and Magnesium Additions on the Microstructure and Mechanical Properties of Al–12Si Alloys

Metals and Materials International - In this study, a binary Al–12Si, eight ternary Al–12Si–Sr, and six quaternary Al–12Si–0.1Sr–(0.2–1)Mg alloys were...     

Microstructure and Properties of Electrodeposited nc-TiO2/Ni–Fe and Ni–Fe Coatings

Metals and Materials International - In this study, nc-TiO2/Ni–Fe composite coatings, and Ni–Fe alloys as equivalents to their matrices, were obtained from citrate-sulphate baths in the...     

Effect of Cd and Sn Addition on the Microstructure and Mechanical Properties of Al-Si-Cu-Mg Cast Alloy

The present work has investigated the effect of trace elements Cd and Sn on the microstructure and mechanical properties of Al-Si-Cu-Mg cast alloy. With the increase of Cd addition the strength of alloy rises at first and then drops. The optimal amount of Cd and Sn addition for AI-Si-Cu-Mg alloy is about 0.27% and 0.1% respectively. Due to the formation of some coarse Cd-rich phases and pure Cd particles the mechanical properties of alloy decrease when Cd amount exceeds 0.27%. When more than 0.1% Sn added, some Sn atoms form low-melting eutectic compound at grain boundary, and then cause over-burning in alloy when solution treated, which may deteriorate properties of alloy, especially ductility of alloy.On the other hand, the addition of Cd and Sn remarkably increases the peak hardness and reduces the time to reach aging peak in Al-Si-Cu-Mg alloy. The action of Cd/Sn in quaternary Al-Si-Cu-Mg alloy is effectively the same as that occur in binary Al-Cu alloy that the enhanced hardening associated with Cd/Sn addition is due to the promotion of the θ‘phase.     

Effect of Extrusion Temperature on the Microstructure and Mechanical Properties of Mg–5Al–2Ca Alloy

In this work, the Mg–5Al–2Ca alloy was extruded at 573, 623 and 673 K, with a ratio of 16:1 and a constant speed of 3 mm/s. Results demonstrate that the Al2Ca particle is formed in Mg–5Al–2Ca alloy. The size, amount and distribution of Al2Ca particles are influenced evidently by extrusion temperature. Unlike previous reports, the intensity of basal texture increases with increasing extrusion temperature, and the reasons are analyzed and given. Even though the average grain size increases as the extrusion temperature increased from 573 to 623 K, the YS, UTS and elongation of asextruded Mg–5Al–2Ca alloy are almost kept the same at 573 and 623 K. The reason is speculated as the balance of grain size, Al2Ca phase and texture at the two temperatures. The work hardening rate depends on extrusion temperature, and the largest θ value of Mg–5Al–2Ca alloy is obtained when the extrusion was performed at 623 K.     

Mechanical Properties and Weld Properties of Beta-21S

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Effect of Partial Recrystallization on Microstructure and Mechanical Properties for Cross-rolled Molybdenum Sheet

The paper presented here reports an appropriate static heat tretment and analyses the microstructure with different partially recrystallized annealing temperatures of cross-rolled molybdenum sheet in order to improve mechanical property of this type of materials and reduce anisotropy at the same time for perspective application. Five different temperature ranges are chosen in this experiment. The samples of a cross-rolled molybdenum sheet are obtained through powder metallurgy, forged ingots and hot or cold rolled sheet. A period of first-stage annealing at 800℃ for one hour is not qualified for the further processing because of bad plasticity, working hardening and crack on the surface. The appropriate second-stage annealing temperature at 950℃ for one hour is chosen for improving the elongation and reduces yield strength. The results show that this appropriate partially recrystallized annealing treatment has achieved the ideal grain size and mechanical properties when it is compared with the other four different temperatures with the same second-stage annealing conditions.     

Effect of V–Ti Addition on Microstructure Evolution and Mechanical Properties of Hot-Rolled Transformation-Induced Plasticity Steel

In order to reveal the effect of V–Ti addition on the microstructure evolution and the mechanical properties of hot-rolled transformation-induced plasticity(TRIP) steel, two steels with 0.072 V–0.051 Ti steel(Bear-V–Ti steel) and 0.001 V–0.001 Ti steel(Free-V–Ti steel) were designed, respectively, and the comparison analyses were carried out by performing thermodynamic calculation and an experiment. With the thermodynamic calculation, the critical annealing temperature of a large fraction of retained austenite(～51%) obtained via solute enrichment was determined, and an optimized quenching at 650 °C and tempering at 200 °C adopted on the as-hot-rolled steel. The results show that the V–Ti TRIP steel displays more optimum mechanical stability during the tensile deformation, since the fraction and the mechanical stability of retained austenite are improved and the microstructure is also ultrarefined by V–Ti alloy precipitation. The yield strength of Bear-V–Ti steel increases from 650 to 800 MPa, and the ductility reaches 37%, showing that the comprehensive mechanical properties are greatly improved.     

Nb含量对Fe0.5MnNi1.5CrNb x 高熵合金微观结构和力学性能的影响

采用真空感应熔炼法制备了Fe_0.5MnNi_1.5CrNb_x（x=0,0.05,0.1,摩尔比）高熵合金,并分析了不同Nb含量对其组织和力学性能的影响。结果表明,不含Nb元素的合金具有单相fcc结构,其抗拉强度和断裂延伸率（即延展性）分别为519 MPa和47%。添加少量的Nb(x=0.05)后出现(200)织构和少量Fe₂Nb Laves相,合金的延展性增加到55%,并且抗拉强度增加到570 MPa。当Nb含量增加到x=0.1时,织构减少,而Fe₂Nb Laves相增多,抗拉强度和延展性分别为650 MPa和45%。     

Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Modified 718 Alloy

M718 alloy with an extra high Mo content of 7.50 wt% which reduced Nb addition and increased Al and Ti additions within the composition specifications of 718 alloy has been designed to increase the service temperature of 718 alloy. And the effect of the heat treatment on the microstructure and mechanical properties of M718 alloy has been investigated in this study. The results showed that Laves phase precipitated on the grain boundaries of M718 alloy instead of d-Ni_3 Nb phase in718 alloy, and y'and y'phases precipitated in the matrix of M718 alloy as that in 718 alloy. Increasing the solution temperature from 960 to 1050 ℃ noticeably reduced the intergranular precipitation of Laves phase. The precipitation of Laves phase was appropriate at 1020 ℃ for improving the grain boundary cohesion. Increasing the two-stage aging temperatures markedly increased the sizes of y' andy'phases. As a result, the strength of M718 alloy increased.     

Effect of Nb Content on Microstructure and Mechanical Properties of Mo0.25V0.25Ti1.5Zr0.5Nbx High-Entropy Alloys

High-entropy alloys (HEAs) have significant application prospects as promising candidate materials for nuclear industry due to their excellent mechanical properties, corrosion resistance and irradiation resistance. In this work, the Mo_0.25V_0.25Ti_1.5Zr_0.5Nb_x(x=0, 0.25, 0.5, 0.75 and 1.0) HEAs were designed and fabricated. The alloys were prepared by vacuum arc melting, and all the ingots were annealed at 1200°C for 24 h. The microstructures, ...     

Microstructure and Mechanical Properties of Unidirectional W Filament Reinforced Al-6Ti-6Nb and SiCp-Al-6Ti-6Nb Matrix Composites

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Effect of Alloyed Mo on Mechanical Properties,Biocorrosion and Cytocompatibility of As-Cast Mg-Zn-Y-Mn Alloys

The influences of Mo contents on mechanical properties,biocorrosion and cytocompatibility of as-cast Mg-6Zn-8.16Y-2.02Mn-xMo(x=0.0,0.1,0.3,0.5,0.7 wt%) alloys were firstly investigated.Appropriate amount of Mo was conducive to grain refinement and the formation of long-period stacking ordered structure with continuous distribution,which was advantageous to mechanical properties and corrosion resistance.Mg-6Zn-8.16Y-2.02Mn-0.3Mo exhibited the ultimate tensile strength of 265.0 MPa,elongation of 13.5% and the lowest weight loss rate in Hank's solution.Moreover,the cell toxicity cultured in 25% extract was evaluated and the alloy with 0.3 wt% Mo exhibited the best cytocompatibility.Thus,the alloy was expected to become a novel biodegradable implant material.     

铁神一号净化剂对灰铸铁组织和力学性能的影响

利用中频感应电炉熔炼灰铸铁铁液，水玻璃砂造型，浇注铸造阶梯试样、φ30mm试棒以及热分析试样，研究了净化剂对其结晶过冷度、组织和力学性能的影响。试验结果表明，单独加入净化剂0．6％可以增加过冷倾向，细化石墨，降低断面敏感性；可以提高灰铸铁的抗拉强度和冶金质量指标；同时加入净化剂0．6％和硅钡孕育剂0．7％对灰铸铁进行复合孕育，明显增加共晶团数量至441个/cm^2，可以获得细小A型石墨，显著提高灰铸铁的力学性能σb至282MPa。     

铌对高铬锰白口铸铁组织和性能的影响

研究了铌对高铬锰白口铸２的组织和性能的影响规律。结果表明，在高铬锰白口铸铁中加入微量的铌能细化晶粒。改善碳化物的形貌和分布。当铌加入量为０．２％时，在８５０℃淬火，力学性能获得最佳配合，冲击韧度为７ｊ／ｃｍ＾２，硬度的６２ＨＲＣ。     

热处理对Al-Si-Mg-Cr合金微观组织与力学性能及耐腐蚀性能的影响

本文采用真空电磁感应熔炼炉制备了Al-Si-Mg-Cr合金,利用Thermo-calc软件进行热力学模拟,使用SEM、EDS等测试方法,表征了不同热处理状态下Al-Si-Mg-Cr合金微观组织,并测试其力学性能。采用了失重法和电化学法测试其腐蚀性能。结果表明：实验合金主要物相包括初晶α-Al、（α-Al+Si）共晶、Al13Cr4Si4、β-Al（Cr, Fe）Si、富Fe相（β-Al5FeSi和π-AlSiMgFe）。热处理后的实验合金组织均得到细化,共晶组织区域变窄,共晶Si球化,合金中Al13Cr4Si4、β-Al（Cr, Fe）Si相弥散分布。腐蚀测试结果显示：实验合金主要的腐蚀方式为晶间腐蚀,热处理后实验合金共晶区域减小,导致腐蚀通道变窄;提高了合金的耐腐蚀性能。当热处理工艺为535℃ 6h+160 26h时,实验合金微观力学性能及耐腐蚀性最佳。     

SiC含量对近β钛合金显微组织及力学性能的影响

通过真空非自耗熔炼工艺制备了不同SiCp添加量(0wt.%、0.1wt.%、0.4wt.%、1.wt.%)的近β钛合金。采用X射线衍射仪(XRD)、扫描电镜(SEM)、维氏显微硬度计和万能材料试验机,系统研究了SiCp添加量对近β钛合金显微组织及力学性能的影响规律。研究结果表明,不同SiCp添加量的近β钛合金主要由α-Ti、β-Ti和TiC所组成。近β钛合金的初生β晶粒尺寸取决于SiCp的添加量,SiCp添加量由0%增加到1wt.%时,近β钛合金初生β晶粒尺寸由639μm降低至323μm。由于受细晶强化、TiC承载强化以及Si的固溶强化的影响,随着SiCp添加量的增加,近β钛合金的显微硬度、压缩强度有显著提高,而压缩率却明显降低。