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An X.,Guizhou University | Liu Q.,Guizhou University | Liu Q.,Key Laboratory for Material Structure and Strength of Guizhou Province | Zheng B.,Guizhou University
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2014

To obtain high performance coating materials, the HEAs MoFeCrTiWAlxSiy coating was prepared on 45# steel by laser cladding. By means of OM, XRD and micro -hardness tester, the microstructure and properties of the high -entropy alloy layer with adding Al and Si element were investigated. The experimental results indicate that the addition of Si element will promote the formation of intermetallic compound, and Al in the coating exhibits obvious the grain refining. In addition, the hardness of the coating is significantly increased, and reaches a maximum (839.3 HV). Adding Al can inhibit the formation of intermetallic compound and induces the simple BCC phase structure of the coating, but the hardness of the coating decrease. Simultaneous addition of Si and Al, the excellent quality coating with detailed microstructure and relatively high hardness can be obtained. Source


Zhu Y.,Guizhou University | Liu Q.,Guizhou University | Liu Q.,Key Laboratory for Material Structure and Strength of Guizhou Province | Jiang H.,Guizhou University | Xu P.,Guizhou University
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2016

β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) are regarded as a kind of biological materials. β-TCP and HA calcium phosphate coatings were prepared on the surface of titanium alloy (Ti6Al4V) by laser cladding technology. The bonding interface, phases and surface morphology of the coating were respectively characterized by optical microscope (OM), X-ray diffraction (XRD) and scanning electronic microscope (SEM). The results showed that an excellent bonding between the ceramic layer and the substrate was ensued by a strong chemical and metallurgical interface. The cladding samples consisted of four parts that were substrate, heat-affected zone, alloyed layer, and ceramic layer region. When the addition of La2O3 reached 0.6%(mass fraction), the coating mainly contained CaTiO3, TiO, β-TCP and HA phases. The surface morphology of the coating was observed by SEM, and the results indicated that the La2O3 contents had a great impact on the coating crack sensitivity. When La2O3 contents was up to 0.6%, the coating surface was smooth with a small amount of holes and cracks, and the hardness value of the coating was HV 1971. © Editorial Office of Chinese Journal of Rare Metals. All right reserved. Source


An X.L.,Guizhou University | Liu Q.B.,Key Laboratory for Material Structure and Strength of Guizhou Province | Zheng B.,Guizhou University
Applied Mechanics and Materials | Year: 2014

To obtain the coating with excellent properties, FeWCrMnCoCuTix (x=0.2, 0.4, 0.6) high entropy alloys coating on 45 steel were prepared by laser cladding. By means of OM, XRD and microhardness tester, the effect of Ti content on microstructure and properties of coating is investigated. The experimental result shows that the phase composition of HEAs coating is simple body-centered cubic and face-centered cubic. The microstructure of these alloys is mainly dendrite crystal with grains were fine and uniform. When Ti content increases to x=0.4, the hardness of the coating reaches a maximum (639HV0.2). © (2014) Trans Tech Publications, Switzerland. Source


Yi Y.-L.,Guizhou University | Yi Y.-L.,Key Laboratory for Material Structure and Strength of Guizhou Province | Liang Y.-L.,Guizhou University | Liang Y.-L.,Key Laboratory for Material Structure and Strength of Guizhou Province | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

Heat treatment of specimen was performed and the transformation temperature was measured by using DIL805A/D differential diameter. Phase structure factor was calculated by the empirical electron theory of solids and molecules (EET). Microstructure, substructure and residual austenite were observed by metallurgical microscope, transmission electron microscope and AMI-21 austenite measuring instrument, respectively. The effect of RE on dynamic transition of GDL-1 steel under air-cooled was investigated. Experimental results show that after adding a certain amount of rare earths, τ/t〈1, and nuclear embryo has not be merged by lateral migration steps, and grow up in the form of sympathetic nucleation to form bainite multi-level fine substructure. RE addition makes Fe-C-RE segregation structural unit of GDL-1 steel increase and the values of phase structure factor (nA, FCD) increase. Under this condition, the resistance of Fe-C-RE segregation unit on phase transformation is increased, the forming of granular bainite is inhibited and bainite ferrite microstructure and substructure are finer. Beside this, RE makes the content and stability of residual austenite increase. ©, 2014, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved. Source


Lei L.,Guizhou University | Lei L.,Key Laboratory for Material Structure and Strength of Guizhou Province | Liang Y.,Guizhou University | Liang Y.,Key Laboratory for Material Structure and Strength of Guizhou Province | And 4 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

The quenching treatment of 20CrNi2Mo steel was carried out with different cooling mediums. The effects of cooling rate on microstructure and mechanical properties of 20CrNi2Mo steel were investigated. The results show that with the increase of cooling rate, the grain size of 20CrNi2Mo steel is almost unchanged, and the martensite lath is refined; the strength increases, the elongation and reduction of area remain unchanged. And with the increase of cooling rate, the impact absorbed energy increases and the fracture changes from brittle to ductile. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved. Source

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