Effect Of Neodymium On The Microstructures And Compression Property Of Titanium Foam

Porous material is one of the most promising structural and functional materials that applied in various fields. Titanium and its alloys have the advantages of low density, high specific strength, wide operation temperature, excellent corrosion resistance and biocompatibility. Titanium foam and its alloys contain the advantages of titanium alloys and porous materials, which could effectively lower the weight and never weaken the strength of the materials. By far, titanium foam with different porosity could be successful fabricated in domestic. However, they are still in the laboratory research stage and far away from industrial manufacturer. This paper studies the fabrication process of titanium foam with porosity 30% by powder metallurgy technology for the purpose of improve the mechanical property, modify the sintering condition and finally offer the theoretical foundation of produce the titanium foam with superior property and high porosity. As far as the fabrication process of titanium foam with 30% porosity is concerned, the effect of the pressing pressure, sintering temperature and sintering time on the micro and macro pore of the material and the compression resistance have been studied. In addition, the effect on the different content of neodymium(Nd) to the mixing powder to produce the final sample has also been studied, which mainly includes the porosity, the initial yield strength, Young modulus and microstructure. Aim at improve the properties of titanium foam and modify the sintering condition.The mainly conclusion are showed as follows,1. Appropriate increase compacting pressure—a significant factor during the fabrication process of titanium foam—could increase the density improve the strength of the materials and even hinder the growth of grain. However, the much higher pressure might generate cracks during the sintering process as a result of the rapid disappearance of internal stress and then lower the density and deteriorate the mechanical property. Different basis material and particle size, different content of spacer holder corresponds to the different best pressing pressure. The best pressing pressure of titanium foam with 30% porosity is 200 MPa through the experiment detection.2. As another important factor that influence the property of the samples, sintering temperature is usually defined between 2/3 and 3/4 of the melting point of the basis material. The results demonstrate that the sintering condition gets improved and the mechanical property gets modified as the sintering temperate increases. In this study, the sintering temperature is settled at 1250? and the initial yield strength of the sample reaches to the highest with 374.04 MPa.3. Sintering time, namely holding time during the sintering process, has great effect on the property of samples. The sintering condition and the mechanical property could be improved as the sintering time increases at a certain sintering temperature. However, it has little sense to keep heating if the sintering process has been finished. 2 hours was the best sintering time based on the experiment results.4. The effect of the adding content of Nd on micro pores and macro pores of titanium foams are studied. The results implied that the adding of Nd has little effect on macro pores of titanium foam. On the other hand, the size of micro pores of materials has obviously reduced and gradually becomes globular as the content of Nd increased.5. The result of the porosity of material indicated that the porosity of titanium foam reduced as the content of Nd increases with 0wt% to 4wt%. The main reason is that the adding of Nd could improve the sintering condition and then increase the density of the material that finally reduce the porosity of samples.6. The adding of Nd has a little effect on initial yield strength of material, all the samples have the initial yield strength of about 374 MPa. However, the compressive strain has been apparently increased from 5.21% to 7.15% as the content of Nd increases from 0wt% to 4wt% and therefore improves the molding of the materials. On the other hand, the young modulus of material decreased from 7.19 GPa to 5.24 GPa as the content of Nd increases from 0wt% to 4wt%.7. By adding different content of Nd, it could be concluded that the inexistence of Nd mainly result from the too less adding content, or there was no evidence of Nd existence from the XRD analysis. The addition of Nd has the fine grains effect in the sintering process of titanium foam material, which thus increases the density of the titanium foam and improves its mechanical properties.