In this article,review is made of the present status of application of cast Ti and Ti alloy in dentistry.

The effects of dual-temperature heat treatment on microstructure and mechanical properties of Ti-Al-Cr alloys have been studied.The results show that dual-temperature heat treatment resulted in the fine uniform duplex microstructure,ideal mechanical properties are obtained with σ b=547 MPa,σ 0.2 =632 MPa,δ=3 5%under the heat treatment at 1 290 ℃,4 h,FC→1 240 ℃,4 h,FC+900 ℃,24 h,FC.

Effects of solid solution treatment on mechanical properties of the vacuum-hot-pressed(HP) beryllium material and the cold-hot-isostatic(HIP)beryllium material have been studied by impact grinding of the beryllium powders with stable low-oxygen air.It is shown that the mechanical properties of beryllium materials as solution are lower than that of as-pressed Be by both hot press and HIP.The lower mechanical property of solid-solution hot-pressed Be material is caused mainly by BeO aggregation due to Be 2SO 4 precipitate and also the lower Fe content in the feed,resulting in non-effective solid solution strengthening.

The phase equilibria in the Ni-Ti-Si ternary system at 1 173 K was investigated by using diffusion triple technique and electron microprobe analysis (EMPA).The experimental results indicate that seven diffusion layers, which are TiSi 2, TiSi, Ti 5Si 4, Ti 5Si 3, Ti 3Si, Nb 5Si 3 and NbSi 2,exist in the Ni-Ti-Si ternary system at 1 173 K,and no ternary compound was observed in the diffusion triple.A tentative isothermal section of this system at 1 173 K was constructed based on the experimental data.The isothermal section consists of six three-phase regions.

The removal of molybdenum from crude sodium tungstate solution was investigated by cupric sulphate precipitation with the addition of appropriate quantity of sodium sulfide and under suitable conditions.First,under certain conditions,sodium molybdate was converted into sulphomolybdate preferentially in solution.Then the cupric sulphate was used to precipitate the sulphomolybdate.This method is not only simple,easily controlled but also has little pollution.

ion:The extraction of rare earths by A101 in HCl solution within magnetic field was studied.The principle of extraction was discussed and the effect of magnetic field on extractability was analyzed.The data illustrated the extractability was slightly increased in the magnetic field,which could be explained by the same extraction principle.It is the change of physical properties of system that makes the extractability increase.The magnetic field does not have periodical relationship with the distribution ratio and magnetic length of rare earths.

The recrystallization texture of tantalum wires at 1 100 ℃?1 250 ℃?1 360 ℃?1 500 ℃for 40min was investigated by ODF and the recrystallization mechanic was researched via microstructural and hardness tests.It was found that the recrystallization was completed and the fine grain appeared at 1 360 ℃,the texture component consisted of {110} <001> ,which had a 27°-<110>orientation relationship to the deformation textute {112}<110>.At 1 500 ℃,the exaggerated growth occurred,and a new texture{441}<110>with a 27°<110>orientation relationship to the primary texture{110}<001>was found.A recrystallization model of bcc metal was proposed to explain it.

Research is made on the application of uniform design in metallurgical tests.Based on 3 target data and 4 factors in a test,uniform design is adopted for the test and mechanical models are established for the analysis.The results showed that compared with orthogonal-desgn L(6 4),the adoption of U 6(6 4)uniform design can ensure optimum process data with less tests and the qulitative relationship between the variants is shown,indicating that uniform design is of very importance in the metallargical experiments.

Silica powder was treated by film coating in gas phase and solid phase.The properties such as diffusion nature,whiteness and discoloring power were distinctly improved.The experimental results show the modified silica powder can completely or partially take the place of titanium dioxide.