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In this study, Mg2Si in in-situ Mg2Si/Al composites were subjected to modification treatment using rare earth element Holmium (Ho). The phase composition and microstructure before and after modification of Mg2Si were also analyzed using X-ray diffraction (XRD) and optical microscope (OM); in addition, its mechanical properties were detected as well. The results showed that moderate addition of rare earth element Ho in in-situ Mg2Si/Al composites presents good modification effects on Mg2Si, the morphology of primary Mg2Si was changed from cross shape before modification to dispersed irregular mass; optimal modification effect was obtained when 0.4% rare earth element Ho was added. Under this condition, the average size of primary Mg2Si was decreased from 74 μm before modification to 16 μm; its mechanical properties were promoted significantly; and its tensile strength increased from 134 MPa before modification to 174.6 MPa, its brinell hardness elevated from 76 HB to 90 HB.

The effect of Al-10Sr master alloy modifier with different content on the microstructure and properties of as-cast Al-12.6Si-0.35 Mg alloy was investigated. The results show that, eutectic silicon varies from original needle and flake to fibrous shape; The shape, size, and quantity of α -Al all changed; When Sr content is 0.023%, the modification effect is most ideal, α -Al shows the highest quantity and smallest size. Meanwhile, the tensile strength and elongation of the alloy reach to the optimum values of 248.2 MPa and 7.2% respectively. These two values are 1.34 and 2.77 times higher than the 185 MPa and 2.6% before modification respectively.

122mW green emission at 532.3nm with a conversion efficiency of 1.2% was measured by single-pass second-harmonic generation in a 10mm long periodically poled MgO:LiNbO3 (MgO:PPLN) crystal is reported. A continuous-wave Yb-doped fiber laser operating at 1064.6nm with narrow bandwidth of 0.1nm is used as pumping source. The experimental temperature acceptance bandwidth ΔT=4.6℃ is a little higher than the simulation data of 4℃. Output power instabilities or variations of the green beam pattern were not observed during experiments. In this work, the optimized efficiency was achieved when the waist located at the center of MgO:PPLN and Rayleigh length equal to its length, and the lens’ location in the system was calculated.

In the paper, titanium tri-aluminide (Al3Ti) particles reinforced aluminium (Al)-based composite coatings were fabricated by infiltration plus in-situ techniques at 891.3 °C. The obtained composite coatings are characterized by XRD, SEM and friction and wear testers. The experimental results show that the reaction between Ti wires and Al molten increases with extending time, Ti wires can totally transform into Al3Ti particles for 20 min, which present blocky and strip-like states, respectively. The wear rates of the composite coatings decrease with increasing time.

A kind of (Fe,Cr)7C3particles reinforced iron matrix composite was prepared by metallurgical bonding between Cr wires and gray cast iron at 1200℃ with subsequent heat treatment. The obtained composites were comparatively characterized by XRD, SEM and microhardness tests. The results showed that the composites mainly consisted of α-Fe matrix and the reinforcements of particle bundles, which include (Fe,Cr)7C3 carbides and γ-Fe. The cross-section of the reinforcements gradually increase with heat treatment time, and the microstructures change from eutectic to hypoeutectic, the morphologies of the reinforcements present chrysanthemum-shaped, granular and intercrystalline eutectics.

The microstructure and element distribution of AZ80 magnesium alloy as-cast and after annealing treatment were studied by OM, SEM, XRD, EDS and TEM. The results show that the coarse divorced eutectic phase distributed along the grain boundary dissolve into Mg matrix during the isothermal process at 415℃ for 24h. During the cooling process of annealing treatment, the lameller-shape β-Mg17Al12 nucleated preferentially in the grain near the boundary, then grows towards the neighbor grains with longitudinal direction, which precipitated from magnesium solid solution as perlite-type precipitation. When cooled to room temperature, the lameller-shape β-Mg17Al12 was uniformly distributed in the matrix, and the lamellar spacing inside β phase is about 1-2μm.

In the paper, tungsten carbide (WC) particles can be in-situ synthesized by applying electromagnetic field to the system consisting of tungsten wires and gray cast iron melt at 1573 K. The microstructures and wear-resistant properties of composites reinforced by both WC particles and the residual tungsten wires were investigated by XRD, SEM, EDS, micro-hardness and pin-on-disc wear measurements. The results show that, with enhancing frequencies of electromagnetic field from 0 to 5 KHz, the amounts of in-situ WC particles increased and of the residual tungsten wires gradually decreased until tungsten wires completely reacted. Due to the higher hardness of in-situ WCp(2100-2231HV0.1) and the strong interfacial bonding, the composites displayed an excellent wear-resistant properties. When the frequency was 5 kHz, the wear loss for the composite fabricated was optimal and 2.69 times lower than that of reference samples.