Ana Ramirez-Ledesma; Hugo Lopez F; Julio Juarez-Islas
Abstract
A Co-20 wt. Cr alloy was vacuum induction melted and cast into a wedge shaped copper mold. The resultant microstructures were investigated from sections obtained longitudinally and centrally in the plane normal to the diverging wedge faces. The aim of this work was to produce a microstructure free of ...
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A Co-20 wt. Cr alloy was vacuum induction melted and cast into a wedge shaped copper mold. The resultant microstructures were investigated from sections obtained longitudinally and centrally in the plane normal to the diverging wedge faces. The aim of this work was to produce a microstructure free of interdendritic segregation with minimal or no intermetallic precipitates and suitable for biomedical implant applications. The as-cast microstructure consisted predominantly of columnar dendrites. In particular, the presence of athermal HCP e-martensite and the metastable FCC γ-Co phase were identified by X-ray diffraction means and scanning electron microscopy. It was found that the exhibited volume fraction of athermal e-martensite was over 90 wt. %. In addition, a heat treating below the γ/e transition temperature led to transformation of the athermal e-martensite into a stress-relieved isothermal one. In turn, the resultant tensile properties, ductility and fracture mode of the alloy after the heat treatment exhibited significant changes. Finally, preliminary tests in artificial saliva indicated that the heat-treated alloy possesses appreciable corrosion resistance when compared with other Co-alloys, making it an ideal candidate for dental implants.
Rashmi mittal; Devendra Singh
Abstract
The wear behaviour of Al-12Si alloy and Al-12Si-Sn/ZrSiO4 composite prepared by spray forming technique has been investigated under dry sliding conditions at different loads and temperatures. The wear rate of spray formed composite was significantly lower than that of as cast Al-12Si alloy. Paricle size ...
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The wear behaviour of Al-12Si alloy and Al-12Si-Sn/ZrSiO4 composite prepared by spray forming technique has been investigated under dry sliding conditions at different loads and temperatures. The wear rate of spray formed composite was significantly lower than that of as cast Al-12Si alloy. Paricle size of ZrSiO4 was varied from 53 to 105 µm and the amount of Sn was taken 5 and 10 %. Smaller particles of ZrSiO4 were able to reduce the wear rate up to more extent as compared to that of bigger particles in the same matrix. On increasing the amount of Sn the wear rate decreases.
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