{"id":{"repo_id":"edithcowan","oai_identifier":"oai:ro.ecu.edu.au:theses-3280"},"canonical_url":"https://search.dev.ndltd.org/etd/edithcowan/oai:ro.ecu.edu.au:theses-3280","repository":{"repo_id":"edithcowan","name":"Edith Cowan University","base_url":"https://ro.ecu.edu.au/do/oai/"},"display":{"title":"Microstructure and mechanical behavior of metastable beta type titanium alloys","abstract":"Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because they demonstrate a wide range of superior mechanical, corrosion and biological properties. In this PhD study, the Ti-27Nb-7Fe-xCr (x = 0, 2, 4, 6, 8 wt%) alloys using inexpensive elements (Fe, Mn, Cr etc.) have been designed to check their suitability for biomedical applications, whereas the Ti-33Zr-xFe-yCr (x = 3, 5, 7 and y = 2, 4 wt%), Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) and Ti-xZr-7Fe-ySn (x = 25, 30, 35 and y = 2, 4 wt%) alloys have been designed to check their suitability for high-strength applications. Later, all the investigated alloys have been cast using a cold crucible levitation melting technique. In the Ti-27Nb-7Fe-xCr alloys, only 2 wt% quantity of Cr is enough to retain a single β phase. Young’s moduli of the Ti-27Nb-7Fe-xCr alloys decrease from 116 GPa (in Ti-27Nb-7Fe) to 72 GPa (in Ti-27Nb-7Fe-8Cr) as the β stability improves. The Ti-33Zr-xFe-yCr alloys, except Ti- 33Zr-3Fe-2Cr alloy, demonstrate a C15 type Laves phase and a dominating β phase. Moreover, the Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys show C14 type Laves and β phases. It is quite interesting to investigate the deformation and strength characteristics of hexagonal close-packed C14 and face-centered cubic C15 type Laves phases in the soft β matrix. Therefore, the deformation and strength characteristics of C14 phase in Ti-35Zr-5Fe-6Mn and C15 phase in Ti- 33Zr-7Fe-4Cr, considering the same volume fraction of Laves phase (~7.0%) have been evaluated and compared using a micro-indentation method. Remarkably, dislocation activity and plastic deformation features are evident in the C15 phase, whereas the C14 phase strongly blocks dislocation motion. The Ti-33Zr-xFe-yCr, Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys, designed for high-strength applications, demonstrate yield strength from 1048 to 1580 MPa, ultimate compressive strength from 1498 to 2140 MPa and plastic strain from 2.6 to 33.6%. Further, the appropriate variation in the volume fraction of Laves phase helps in achieving an improved trade-off between strength and plasticity. Moreover, fracture analyses have also been executed for the Ti-33Zr-xFe-yCr, Ti-35Zr- 5Fe-xMn and Ti-xZr-7Fe-ySn alloys. It has been found that the crack propagates along the corresponding Laves phase present in these alloys. The results of the investigated alloys suggest that Ti-27Nb-7Fe-8Cr is suitable for biomedical applications, whereas Ti-33Zr-7Fe-4Cr, Ti-35Zr- 5Fe-8Mn and Ti-35Zr-7Fe-2Sn are suitable for high-strength structural applications. This research is useful to understand the microstructure, mechanical and fracture behavior of titanium alloys used in industries such as biomedical, aerospace, automobile etc.","abstract_html":"Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because they demonstrate a wide range of superior mechanical, corrosion and biological properties. In this PhD study, the Ti-27Nb-7Fe-xCr (x = 0, 2, 4, 6, 8 wt%) alloys using inexpensive elements (Fe, Mn, Cr etc.) have been designed to check their suitability for biomedical applications, whereas the Ti-33Zr-xFe-yCr (x = 3, 5, 7 and y = 2, 4 wt%), Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) and Ti-xZr-7Fe-ySn (x = 25, 30, 35 and y = 2, 4 wt%) alloys have been designed to check their suitability for high-strength applications. Later, all the investigated alloys have been cast using a cold crucible levitation melting technique. In the Ti-27Nb-7Fe-xCr alloys, only 2 wt% quantity of Cr is enough to retain a single β phase. Young’s moduli of the Ti-27Nb-7Fe-xCr alloys decrease from 116 GPa (in Ti-27Nb-7Fe) to 72 GPa (in Ti-27Nb-7Fe-8Cr) as the β stability improves. The Ti-33Zr-xFe-yCr alloys, except Ti- 33Zr-3Fe-2Cr alloy, demonstrate a C15 type Laves phase and a dominating β phase. Moreover, the Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys show C14 type Laves and β phases. It is quite interesting to investigate the deformation and strength characteristics of hexagonal close-packed C14 and face-centered cubic C15 type Laves phases in the soft β matrix. Therefore, the deformation and strength characteristics of C14 phase in Ti-35Zr-5Fe-6Mn and C15 phase in Ti- 33Zr-7Fe-4Cr, considering the same volume fraction of Laves phase (~7.0%) have been evaluated and compared using a micro-indentation method. Remarkably, dislocation activity and plastic deformation features are evident in the C15 phase, whereas the C14 phase strongly blocks dislocation motion. The Ti-33Zr-xFe-yCr, Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys, designed for high-strength applications, demonstrate yield strength from 1048 to 1580 MPa, ultimate compressive strength from 1498 to 2140 MPa and plastic strain from 2.6 to 33.6%. Further, the appropriate variation in the volume fraction of Laves phase helps in achieving an improved trade-off between strength and plasticity. Moreover, fracture analyses have also been executed for the Ti-33Zr-xFe-yCr, Ti-35Zr- 5Fe-xMn and Ti-xZr-7Fe-ySn alloys. It has been found that the crack propagates along the corresponding Laves phase present in these alloys. The results of the investigated alloys suggest that Ti-27Nb-7Fe-8Cr is suitable for biomedical applications, whereas Ti-33Zr-7Fe-4Cr, Ti-35Zr- 5Fe-8Mn and Ti-35Zr-7Fe-2Sn are suitable for high-strength structural applications. This research is useful to understand the microstructure, mechanical and fracture behavior of titanium alloys used in industries such as biomedical, aerospace, automobile etc.","abstract_has_math":false,"creators":["Rabadia, Chirag Dhirajlal"],"institution":"Edith Cowan University, Research Online, Perth, Western Australia","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-01-01T08:00:00Z","date_published":"2020-01-01T08:00:00Z","updated_at":"2026-07-27T19:21:17Z","subjects":["Titanium alloys","Mechanical properties","Microstructure","Deformation","Fracture analysis","Engineering","Materials Science and Engineering","Mechanical Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://ro.ecu.edu.au/theses/2278","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Rabadia, Chirag Dhirajlal"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-01-01T08:00:00Z"]},{"key":"dc:publisher","label":"Institution","values":["Edith Cowan University, Research Online, Perth, Western Australia"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Titanium alloys","Mechanical properties","Microstructure","Deformation","Fracture analysis","Engineering","Materials Science and Engineering","Mechanical Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://ro.ecu.edu.au/theses/2278","https://ro.ecu.edu.au/context/theses/article/3280/viewcontent/RABADIA_Chirag_Revised_final_version_of_PhD._Thesis_07_01_2020_Redacted1.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because they demonstrate a wide range of superior mechanical, corrosion and biological properties. In this PhD study, the Ti-27Nb-7Fe-xCr (x = 0, 2, 4, 6, 8 wt%) alloys using inexpensive elements (Fe, Mn, Cr etc.) have been designed to check their suitability for biomedical applications, whereas the Ti-33Zr-xFe-yCr (x = 3, 5, 7 and y = 2, 4 wt%), Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) and Ti-xZr-7Fe-ySn (x = 25, 30, 35 and y = 2, 4 wt%) alloys have been designed to check their suitability for high-strength applications. Later, all the investigated alloys have been cast using a cold crucible levitation melting technique. In the Ti-27Nb-7Fe-xCr alloys, only 2 wt% quantity of Cr is enough to retain a single β phase. Young’s moduli of the Ti-27Nb-7Fe-xCr alloys decrease from 116 GPa (in Ti-27Nb-7Fe) to 72 GPa (in Ti-27Nb-7Fe-8Cr) as the β stability improves. The Ti-33Zr-xFe-yCr alloys, except Ti- 33Zr-3Fe-2Cr alloy, demonstrate a C15 type Laves phase and a dominating β phase. Moreover, the Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys show C14 type Laves and β phases. It is quite interesting to investigate the deformation and strength characteristics of hexagonal close-packed C14 and face-centered cubic C15 type Laves phases in the soft β matrix. Therefore, the deformation and strength characteristics of C14 phase in Ti-35Zr-5Fe-6Mn and C15 phase in Ti- 33Zr-7Fe-4Cr, considering the same volume fraction of Laves phase (~7.0%) have been evaluated and compared using a micro-indentation method. Remarkably, dislocation activity and plastic deformation features are evident in the C15 phase, whereas the C14 phase strongly blocks dislocation motion. The Ti-33Zr-xFe-yCr, Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys, designed for high-strength applications, demonstrate yield strength from 1048 to 1580 MPa, ultimate compressive strength from 1498 to 2140 MPa and plastic strain from 2.6 to 33.6%. Further, the appropriate variation in the volume fraction of Laves phase helps in achieving an improved trade-off between strength and plasticity. Moreover, fracture analyses have also been executed for the Ti-33Zr-xFe-yCr, Ti-35Zr- 5Fe-xMn and Ti-xZr-7Fe-ySn alloys. It has been found that the crack propagates along the corresponding Laves phase present in these alloys. The results of the investigated alloys suggest that Ti-27Nb-7Fe-8Cr is suitable for biomedical applications, whereas Ti-33Zr-7Fe-4Cr, Ti-35Zr- 5Fe-8Mn and Ti-35Zr-7Fe-2Sn are suitable for high-strength structural applications. This research is useful to understand the microstructure, mechanical and fracture behavior of titanium alloys used in industries such as biomedical, aerospace, automobile etc."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:source","label":"Dc Source","values":["Theses: Doctorates and Masters"]},{"key":"dc:title","label":"Title","values":["Microstructure and mechanical behavior of metastable beta type titanium alloys"]}]}],"canonical_facts":{"dc:creator":["Rabadia, Chirag Dhirajlal"],"dc:date":["2020-01-01T08:00:00Z"],"dc:description":["Current biomaterials such as stainless steel, Co-Cr alloys, commercially pure titanium and Ti-6Al- 4V either possess poor mechanical compatibility and/or produce toxic effects in the human body after several years of usage. Consequently, there is an enormous demand for long-lasting biomaterials which provide a better combination of mechanical, corrosion and biological properties. In addition to this, alloys used in high-strength applications possess either high-strength or large plasticity. However, a high-strength alloy should possess a better blend of both strength and plasticity when used in high-strength applications. Metastable β-titanium alloys are the best suited alloys for biomedical and high-strength applications because they demonstrate a wide range of superior mechanical, corrosion and biological properties. In this PhD study, the Ti-27Nb-7Fe-xCr (x = 0, 2, 4, 6, 8 wt%) alloys using inexpensive elements (Fe, Mn, Cr etc.) have been designed to check their suitability for biomedical applications, whereas the Ti-33Zr-xFe-yCr (x = 3, 5, 7 and y = 2, 4 wt%), Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) and Ti-xZr-7Fe-ySn (x = 25, 30, 35 and y = 2, 4 wt%) alloys have been designed to check their suitability for high-strength applications. Later, all the investigated alloys have been cast using a cold crucible levitation melting technique. In the Ti-27Nb-7Fe-xCr alloys, only 2 wt% quantity of Cr is enough to retain a single β phase. Young’s moduli of the Ti-27Nb-7Fe-xCr alloys decrease from 116 GPa (in Ti-27Nb-7Fe) to 72 GPa (in Ti-27Nb-7Fe-8Cr) as the β stability improves. The Ti-33Zr-xFe-yCr alloys, except Ti- 33Zr-3Fe-2Cr alloy, demonstrate a C15 type Laves phase and a dominating β phase. Moreover, the Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys show C14 type Laves and β phases. It is quite interesting to investigate the deformation and strength characteristics of hexagonal close-packed C14 and face-centered cubic C15 type Laves phases in the soft β matrix. Therefore, the deformation and strength characteristics of C14 phase in Ti-35Zr-5Fe-6Mn and C15 phase in Ti- 33Zr-7Fe-4Cr, considering the same volume fraction of Laves phase (~7.0%) have been evaluated and compared using a micro-indentation method. Remarkably, dislocation activity and plastic deformation features are evident in the C15 phase, whereas the C14 phase strongly blocks dislocation motion. The Ti-33Zr-xFe-yCr, Ti-35Zr-5Fe-xMn and Ti-xZr-7Fe-ySn alloys, designed for high-strength applications, demonstrate yield strength from 1048 to 1580 MPa, ultimate compressive strength from 1498 to 2140 MPa and plastic strain from 2.6 to 33.6%. Further, the appropriate variation in the volume fraction of Laves phase helps in achieving an improved trade-off between strength and plasticity. Moreover, fracture analyses have also been executed for the Ti-33Zr-xFe-yCr, Ti-35Zr- 5Fe-xMn and Ti-xZr-7Fe-ySn alloys. It has been found that the crack propagates along the corresponding Laves phase present in these alloys. The results of the investigated alloys suggest that Ti-27Nb-7Fe-8Cr is suitable for biomedical applications, whereas Ti-33Zr-7Fe-4Cr, Ti-35Zr- 5Fe-8Mn and Ti-35Zr-7Fe-2Sn are suitable for high-strength structural applications. This research is useful to understand the microstructure, mechanical and fracture behavior of titanium alloys used in industries such as biomedical, aerospace, automobile etc."],"dc:format":["application/pdf"],"dc:identifier":["https://ro.ecu.edu.au/theses/2278","https://ro.ecu.edu.au/context/theses/article/3280/viewcontent/RABADIA_Chirag_Revised_final_version_of_PhD._Thesis_07_01_2020_Redacted1.pdf"],"dc:publisher":["Edith Cowan University, Research Online, Perth, Western Australia"],"dc:source":["Theses: Doctorates and Masters"],"dc:subject":["Titanium alloys","Mechanical properties","Microstructure","Deformation","Fracture analysis","Engineering","Materials Science and Engineering","Mechanical Engineering"],"dc:title":["Microstructure and mechanical behavior of metastable beta type titanium alloys"],"dc:type":["thesis"]},"updated_at":"2026-07-27T19:21:17Z"}