Study is made of the effect and refinement mechanism of rare earth element on Al-Ti-B-RE refiners prepared by casting of pure Ti particle.The results show that the addition of rare-earth element can improve the wetting quality of the molten Al to TiB2 and TiAl3 phase,and heterogeneous nucleation ability and delay decay time.The refinement result of different refiners mainly depends on the characteristic of TiB2 and TiAl3 grains,especially the morphologysize and quantity of TiAl3 phase.The refiners containing massive,small and dispersible lumpy TiAl3 phase work well,and TiB2 phase is the main factor affecting the effective nucleation quantity of α-Al.The Al-Ti-B-RE refiners are superior to Al-Ti-B refiners made both at home and abroad in respect of the refinement result and anti-recession ability.

AlTiC master alloys were prepared by aluminum-thermal reduction.Analysis is made of the composition,microstructure and morphology of the AlTiC master alloys through X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Study is made of the refinement of the commercial pure Al by the self-developed AlTiC grain master alloy and the refining results are analyzed and compared through optical microscope and refining mechanism is preliminarily discussed.The test results show that the refining effect of AlTiC master alloy is better than that of the domestic AlTiB master alloy.

Surface Nb impregnation on TC11-based alloy is done by DGPSAT process.Microstructure,composition,phases and elastic modulus of the Nb-impregnated TC11 alloy layer were analyzed through scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD） and nanoindenter tester respectively.The result indicated that the Nb element is distributed in graded pattern throughout the impregnation layer layer,which are mainly composed of Nb substituted solid solution formed in β-Ti（Nb） and AlNb2 phase effective thickness of the impreganation layer was up to 14 μm.After Nb impregnation,the nano-hardness of TC11 was 1.9 times higher,while the elastic modulus was slightly lower than that of the substrate.

La2O3-doped Mo-12Si-8.5B alloys with different mass fraction of lanthanum oxide were prepared by liquid-liquid doping and plasma activated sintering technology.The phase analysis and observation of microstructures of Mo-Si-B alloys are conducted through XRD and optical microscope.And the mechanical property of alloy is tested.Results show that the Mo-Si-B alloys mainly consist of α-Mo,Mo3Si and Mo5SiB2 three phases,and the microstructure of the doped Mo-Si-B alloy was refined and the compressive strength was improved with the increasing of La oxide doped.

Six（6） groups of WC-Co carbides with different Mo content were manufactured by powder metallurgy.The mechanical properties were measured at room temperature,and the phase structure and microstructure were studied through XRD,SEM and EDS.The result shows that the small addition of Mo can refine WC grain improve the relative density and hardness;but flexural strength is reduced.When the Mo addition reaches 2.4%,the material has the best microstructure and mechanical property.

Analysis is made of the basic process such as relative density,pre-pressure,delay time,densification pressure,dwell time etc of the pretreated blanks and the relationship between the effect of and on the material performance in the process of preparing（Ni,Cf）/TiC-TiB2 ceramic-based compound material by SHS/PHIP.The results show that densification pressure,content of Ni and carbon fiber are the main factors affecting the material performance.Thus,orthogonal of was designed.The test results show that the sample（120 g） will have best performance when carbon fiber content is 3 wt%,Ni content 15 wt%,of the pretreated blanks relative density 61%,delay time 16 s,densification pressure 300 MPa,dwell time 6 s.It is up to σb=488.27 MPa,KIC=12.90 MPa·m1/2.

Study is made on the effect of solution heat treatment process on mechanical properties,the tensile curve and fracture morphology of SiCP/Al composites with the high volume fraction by means of metallographic analysis,Vickers hardness test,tensile test and TEM.The results show that the strength and toughness of composites are in the best condition when the solution temperature is 528 ℃,and the notch bending resistance displacement curve appears flat at high stress,indicating the possibility of improving the material strength and toughness and reducing tendency of the instantaneous destructive fracture through the optimization of the soild-solution treatment parameters.

Research is conducted on the fracture behaviors of rare earth La2O3-doped Mo plate.The results show that the fracture is originated from the grain inside.In the process of the crack growth,the second phase of rare earth grain plays a vital role in delaying crack growth.