IUMRS International Conference in Asia

Paper Title Page

Authors: Tong Hui Liu, Sheng Ping Wen, Xiao Lan Wu, Hui Huang, Kun Yuan Gao
Abstract: Vickers hardness and electric conductivity measurements as well as micro-structure analysis were used to investigate the effects of trace element Hf atoms on the precipitation and recrystallization resistance in Al-Er-Zr alloys. The results of the present study indicated that the behaviors of precipitation process in Al-0.04Er-0.08Zr and Al-0.04Er-0.08Zr-0.05Hf (at. %) alloys are similar. When alloys were annealed at 350 °C for 96h, the nanoscale and coherent Al3(Er, Zr) and Al3(Er, Zr, Hf) precipitates form, corresponding to the peak hardness values of 56.2 ± 0.9 (ternary alloy), 58.9 ± 1.5 HV (quaternary alloy), respectively. The higher peak hardness in Al-0.04Er-0.08Zr-0.05Hf alloys mainly benefit from the decomposition of Hf. It was shown that the existence of precipitates could improve the recrystallization resistance obviously. Due to the similar retarding force, recrystallization temperatures of both alloys are almost the same, approximate 450 °C.
Authors: Ya Liu, Hui Huang, R. Liu, Sheng Ping Wen, Xiao Lan Wu, Kun Yuan Gao, Zuo Ren Nie
Abstract: The hot deformation behavior of aluminum alloy 5E61 was studied by hot compressive tests using a Gleeble-1500 thermal simulator. The tests were performed at temperatures varying from 250°C to 500°C and strain rates ranging from 0.001 s-1 to 10s-1. The results achieved in the present study showed that the steady flow stress increases with decreasing temperature and increasing strain rate, in accordance with the Zener-Hollomon parameter. The related microstructure is sensitive to deformation temperature, strain rate and strain. The constitutive equation based on true stress-true strain curves has been developed by hyperbolic sine equation with the hot deformation activation energy of 153.907KJ/mol. The softening mechanism could be ascribed dominantly to dynamic recovery. The results of TEM observation suggested that Mn-containing particles and Al3(Er,Zr) phase have precipitated in the aluminum matrix and pin the dislocations, which could effectively inhibit the dynamic recrystallization.
Authors: Xin Fang Bai, Yong Qing Zhao, B. Li
Abstract: In this work the texture evolution of a near β Ti-3Zr-2Sn-3Mo-25Nb (TLM) biomedical titanium alloy in hot compression at different deformation temperatures from 750°C to 850°C has been investigated. The XRD examination shows that the samples of hot deformation consist of β phase only. The development of texture has been explained in terms of orientation distribution functions (ODFs) of α and γ fibres. Compared with cold compression of TLM alloy, the texture changes obviously with the increase of deformation temperature. The {111}<110> texture shows the feature that weaken firstly and then strengthen, while the {111}<112> texture shows an opposite tendency. Specifically, the prominent texture components change to the {111}<110> and {111}<112> at the deformation temperature of 850°C, which are the same texture type and the nearly level of orientation density with the starting materials.
Authors: Tian Yang Guan, Zhi Feng Zhang, Yue Long Bai, Ping Wang
Abstract: The application of Annular Electromagnetic Stirring (A-EMS) for production of high-quality slurry has been examined. Al-11%Zn-3%Mg-1%Cu-0.13%Zr alloy was used to investigate the effect of A-EMS at various temperatures above liquidus on structure refinement. The results indicate that the grain size was reduced greatly and the homogeneous structure was achieved. Instead of the case in tradition, the nucleation particles gradually formed and the enhanced grain refining efficiency can be mainly attributed to an instantaneous nucleation of numerous heterogeneous nucleation of Al3Zr in the superheating melt under A-EMS.
Authors: Pei Liang Liu, Xiao Lan Wu, Sheng Ping Wen, Hui Huang, Kun Yuan Gao, Zuo Ren Nie
Abstract: The microstructure of Al-6Mg-0.9Mn-0.07Zr-0.2Er (wt.%), registered as 5E61 alloy, were investigated using optical microscopy, scanning electron microscopy and transmission electron microscopy. The results showed that the addition of 0.2 wt.% Er can refine the dendritic structure and form fine and coherent L12 structured Al3(ErxZr1-x) precipitates in the alloy. After a two-stage homogenization (280°C/10h, 460°C/36h), the recrystallization temperature of the alloy with 0.2 wt.% Er is about 15°C higher than that of the alloy without Er. The better recrystallization resistance may be related to the Al3(ErxZr1-x) precipitates, which can pin on dislocations and sub-grain boundaries. The hardness of the cold-rolled alloy with 0.2 wt.% Er is 143HV, which is 5% higher than the alloy without Er. The exfoliation corrosion and nitric acid mass loss test were also performed. The exfoliation corrosion of the alloy is N grade, and the mass loss is only 9.84mg/cm2.
Authors: Wen Jian Lv, Bo Long Li, Peng Qi, Zuo Ren Nie
Abstract: The 6061 aluminum alloys with different content of erbium were prepared. The erbium content was optimized by measurement of grain refining effects and tensile strength. After solid solution treatment of the alloy with optimized erbium content at 505 °C ~ 595 °C for 4 h. and then ageing at –160 °C ~ 200 °C for 3 h., the grain size decreased with the content of erbium, achieving the most effective grain size refinement at the erbium content of 0.15wt.%. The tensile strength of as-cast alloy could reach up to 243 MPa at the erbium content of 0.15%. -Combined with the microstructures and mechanical properties, the erbium content of 0.15% was the optimized content, and heat treatments of ageing at 180 °C for 3 h. followed by solid solution at 565 °C for 4 h were suggested.
Authors: Quan Tong Yao, Meng Nan Xing, Guang Lan Zhang, Wei Ping Tong
Abstract: A pollution-free nanocrystalline layer was prepared on the surface of Ti6Al4V by surface mechanical attrition treatment (SMAT). The nanocrystalline samples were vacuum annealed at various temperatures and for different periods of time. The microstructure and thermal stability were characterized by X-ray (XRD), scanning electron microscopy (SEM) and, transmission electron microscopy (TEM). The results showed that the nanocrystalline Ti6Al4V presented a satisfactory thermal stability with the annealed temperature below 650°C. The critical growth temperature for nanocrystalline Ti6Al4V is 100°C higher than that for pure titanium.
Authors: Sha Sha Dong, Bo Long Li, Wen Jian Lv, Peng Qi, Zuo Ren Nie
Abstract: The microstructure and mechanical properties of as-homogenized 6061 aluminum alloy with 0.2wt.% Er were investigated. The microstructures of the as-casted and homogenized alloys were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). Energy dispersion X-ray spectroscopy (EDS) was used to analyze the phase chemical composition. The results showed that the homogenizing treatment had a significant influence on the precipitate morphology of the alloy. With increasing homogenization temperature, the long strip-like Fe-rich grain distributed on the boundary phase became discontinuous and sparseness, transforming to short rod and granular shape. In addition, the Fe-rich phase with a large fish-bone structure became smaller. During homogenizing treatment, a large number of dispersive Mg2Si phase appeared inside grains, and large number of the phases containing Er were dissolved into the matrix.
Authors: Shu Jing Cui, Hao Ran Geng, Xin Ying Teng, Xiang Wei Wu, Peng Jia, Chen Wu
Abstract: As-cast Mg-3Er-xZn (x = 0, 0.5, 1 and 2 at.%) alloys were prepared by a cast ingot metallurgy process. The effect of Zn contents on the microstructure and phase constitution of the alloys was investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electronic microscope (TEM). The results revealed that the as-cast Mg-3Er alloy mainly consisted of α-Mg phase and MgEr eutectic phase. Typically, a small amounts of LPSO phase was precipitated at grain boundaries by adding 0.5 at.% Zn into Mg-3Er alloy. With the addition of 1 at.%Zn, the volume fraction of LPSO phase increased obviously. When the addition of Zn increased to 2 at.%, the volume fraction of LPSO phase decreases and Mg8ZnEr phase forms at grain boundaries. Tensile test indicated that Mg-3Er-1Zn alloy exhibits the excellent mechanical properties. The tensile strength, yield strength and elongation of Mg-3Er-1Zn alloy are 213 MPa, 187.6 MPa and 5.52%, increased by 38.8%, 60% and 3.19%, respectively, corresponding to the alloy without Zn addition. The excellent mechanical properties could be attributed to the introduction of Zn element in alloys, which leads to the strengthening of LPSO phase and grain refinement of α-Mg.
Authors: Wen Jun Liu, Bin Jiang, Xiao Wei Yu, Fu Sheng Pan
Abstract: The influence of cooling rate (1.5, 0.3 and 0.1 °C/s) on the hot tearing susceptibility (HTS) of Mg-9Al-1Zn-0.8Ce alloy was investigated by taking advantage of numerical simulation and experimental methods. Filling and solidification processes were observed directly using AnyCasting software. The results demonstrated that the reduction of cooling rate increases the residual melt modulus, deteriorate strain and stress concentration at last stage of solidification, and decrease the hot tearing resistance of alloy finally. The maximum value of HTS was obtained at the average cooling rate of 0.1 °C/s owing to the coarse microstructures and bulk Al11Ce3. The minimum value of HTS appeared at the rate of 1.5 °C/s thanks to the finest microstructures and a large amount of eutectic. With the increase of cooling rate, hot tearing susceptibility of the alloy shows a rapid reduction at beginning, and a slow decline followed. Besides, morphology of fracture surface and distribution of secondary phase were further discussed.

Showing 1 to 10 of 340 Paper Titles