Study of the preparation of compact materials by methods based on severe plastic deformation

Abstract

This thesis is focused on investigation of the influences of intensive plastic deformation on consolidation and structural changes in samples pre-sintered from powder particles. The first part provides basic information about powder metallurgy, its pros and cons and the mostly used compression methods, as well as describes the principles of methods of intensive plastic deformation, their aims and focuses and also deals with the basic technologies and their possibilities of application on powder-based materials. The experimental part deals with several materials representing the constructional and biomedical fields. From the constructional field, the investigated materials are Al(-Al2O3), Al-25Cu, Al-4Cu-1Mg and Al-9Cu-1Mg. The biomedical group is represented by Ti-25Ta and Ti-35Nb-xZr samples. The first experiment dealing with Al powder was also aimed at examination of suitable conditions for compaction, sintering and consolidation of the used powder materials. The studies of the consolidated materials were generally focused mostly on microstructural investigations and investigations of properties, such as density and microhardness. HPT has proven a favourable influence on consolidation of powder-based samples. However, swaging has also a significant influence on decreasing porosity and increasing mechanical properties. The results achieved within this work can be applied for other SPD technologies such as ECAP, although certain restrictions such as different geometrical conditions and deformation modes have to be taken into account.

This thesis is focused on investigation of the influences of intensive plastic deformation on consolidation and structural changes in samples pre-sintered from powder particles. The first part provides basic information about powder metallurgy, its pros and cons and the mostly used compression methods, as well as describes the principles of methods of intensive plastic deformation, their aims and focuses and also deals with the basic technologies and their possibilities of application on powder-based materials. The experimental part deals with several materials representing the constructional and biomedical fields. From the constructional field, the investigated materials are Al(-Al2O3), Al-25Cu, Al-4Cu-1Mg and Al-9Cu-1Mg. The biomedical group is represented by Ti-25Ta and Ti-35Nb-xZr samples. The first experiment dealing with Al powder was also aimed at examination of suitable conditions for compaction, sintering and consolidation of the used powder materials. The studies of the consolidated materials were generally focused mostly on microstructural investigations and investigations of properties, such as density and microhardness. HPT has proven a favourable influence on consolidation of powder-based samples. However, swaging has also a significant influence on decreasing porosity and increasing mechanical properties. The results achieved within this work can be applied for other SPD technologies such as ECAP, although certain restrictions such as different geometrical conditions and deformation modes have to be taken into account.