Karl U Kainer | Helmholtz-Zentrum Geesthacht (original) (raw)
Papers by Karl U Kainer
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002
Creep experiments were undertaken to determine the potential for using acoustic emission (AE) to ... more Creep experiments were undertaken to determine the potential for using acoustic emission (AE) to monitor the high temperature deformation of an unreinforced AZ91 magnesium alloy and a similar alloy reinforced with short alumina fibers after a conventional T6 heat treatment. Samples of each material were tested to failure and the fracture surfaces of selected specimens were examined using scanning electron
Journal of the Mechanical Behavior of Biomedical Materials, 2012
Mg-Dy alloys have shown to be promising for medical applications. In order to investigate the inf... more Mg-Dy alloys have shown to be promising for medical applications. In order to investigate the influence of ageing treatment on their mechanical and corrosion properties, three Mg-xDy alloys (x=10, 15, 20 wt%) were prepared. Their microstructure, mechanical and corrosion behavior were investigated. The results indicate that ageing at 250 °C has little influence on the mechanical and corrosion properties. In contrast, ageing at 200 °C significantly increases the yield strength, and reduces the ductility. After ageing at 200 °C, the corrosion rate of Mg-20Dy alloy increases largely in 0.9 wt% NaCl solution, but remains unchanged in cell culture medium.
Advanced Engineering Materials, 2000
Skip to Main Content. There will be a release of Wiley Online Library scheduled for Saturday 27th... more Skip to Main Content. There will be a release of Wiley Online Library scheduled for Saturday 27th November 2010. Access to the website will be disrupted as follows: New York 0630 EDT to 0830 EDT; London 1130 GMT to 1330 GMT; Singapore 1930 SGT to 2130 SGT. ...
Advanced Engineering Materials, 2006
Springer Handbook of Condensed Matter and Materials Data, 2005
ABSTRACT
Fundamentals of Magnesium Alloy Metallurgy, 2013
Mathaudhu/Magnesium, 2012
Czechoslovak journal of …, 1999
This paper describes the influence of thermal cycling on the damping behaviour of composites with... more This paper describes the influence of thermal cycling on the damping behaviour of composites with Mg matrix and two contents (26.0 and 34.1 vol.%) of Saffil short fibres. The composites were prepared by squeeze casting. The logarithmic decrement, as a characteristic of the process responsible for the damping behaviour, was measured after ten thermal cycles between room temperature and an upper temperature. The upper temperature was varied within the range from 100 to 450°C.
Materials Science Forum, 2005
ABSTRACT
Journal of the Mechanical Behavior of Biomedical Materials, 2015
ABSTRACT Magnesium alloys are promising candidates for biomedical applications. In this work, inf... more ABSTRACT Magnesium alloys are promising candidates for biomedical applications. In this work, influences of composition and heat treatment on the microstructure, the mechanical properties and the corrosion behavior of Mg-Gd-Ca-Zr alloys as potential biomedical implant candidates were investigated. Mg5Gd phase was observed at the grain boundaries of Mg-10Gd-xCa-0.5Zr (x=0, 0.3, 1.2wt%) alloys. Increase in the Ca content led to the formation of additional Mg2Ca phase. The Ca additions increased both the compressive and the tensile yield strengths, but reduced the ductility and the corrosion resistance in cell culture medium. After solution heat treatment, the Mg5Gd particles dissolved in the Mg matrix. The compressive strength decreased, while the corrosion resistance improved in the solution treated alloys. After ageing at 200°C, metastable β' phase formed on prismatic planes and a new type of basal precipitates have been observed, which improved the compressive and tensile ultimate strength, but decreased the ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.
KAINER:MAGN.ALLOYS APPL. O-BK, 2000
ABSTRACT The object of this paper is to report on thermal fatigue of some very recently developed... more ABSTRACT The object of this paper is to report on thermal fatigue of some very recently developed Mg-based composites. Particularly, the influence of the reinforcement and crystallographic structure of the matrix are analyzed. A similar study of an Al based MMC is reported and the results are compared with those on Mg based MMCs.
Key Engineering Materials, 1997
Materials Science Forum, 2011
Permanent mold casting is a well-established route for casting large magnesium alloys components.... more Permanent mold casting is a well-established route for casting large magnesium alloys components. Casting parameters like superheat, mold temperature, and holding time can often result in inhomogeneous properties, porosity, and segregation problems in the cast part. In order to optimize the casting process, control of the casting parameters including mold temperatures and holding times is essential to promote directional solidification, and ensure defect free homogenous structure. Binary Mg-9wt.%Al and Mg-10wt.%Gd alloys were used to investigate the effect of casting parameters such as melt temperature and holding time on the part macro and microstructure.
Scripta Materialia, 1997
ABSTRACT Many Mg-based metal matrix composites (MMCs) have been developed and manufactured during... more ABSTRACT Many Mg-based metal matrix composites (MMCs) have been developed and manufactured during the last decade as prospective light high-performance constructional materials. When a MMC is submitted to temperature changes (cooling down from the temperature of fabrication, cyclic temperature changes during operation of structural parts) thermal stresses arise at the interfaces owing to a considerable mismatch of the thermal expansion coefficient of the matrix and that of the reinforcement. Even slight temperature changes may produce thermal stresses which exceed the matrix yield stress, consequently, generating new dislocations at the interfaces causing microstructural changes and plastic deformation of the matrix. Long-term exposure may also result in fatigue damage. It is noteworthy that the effect of temperature variations is similar to creep under non-stationary loading conditions. Acoustic emission (AE) has been observed during thermal cycling of Mg based MMCs. Since dislocation motion and microstructural damage are generally accepted to produce AE, it is possible by AE measurements to identify and to characterize the microstructural changes and to correlate them with temperature or other parameters. The dilatometry technique enables the degree of matrix plastic deformation which superposing the thermal expansion to be determined by measuring the shape changes during testing. The combination of both methods yields non-destructively, at any instant of the test, information on the structure and operating processes over the entire volume of the specimen. This can also provide valuable information for subsequent investigations by microscopy or internal friction. The object of this paper is to report on the recently developed, combined AE and dilatometry technique and its application in a structural evolution in Mg-based MMCs subjected to thermal cycling.
JOM, 2007
... Randy S. Beals, Cam Tissington, Xinmin Zhang, Karl Kainer, Joe Petrillo, Mark Verbrugge, and ... more ... Randy S. Beals, Cam Tissington, Xinmin Zhang, Karl Kainer, Joe Petrillo, Mark Verbrugge, and Mihriban Pekguleryuz ... As a focal point of the 2007 TMS Annual Meeting in Orlando, Florida, the TMS Magnesium Committee held its first plenary session with expert representatives ...
Journal of Alloys and Compounds, 2004
The present paper deals with the analysis of the deformation behavior of differently extruded mag... more The present paper deals with the analysis of the deformation behavior of differently extruded magnesium alloys taken from the AZ series. Rods were extruded using indirect and hydrostatic extrusion which results in a different behavior with respect to mechanical properties and microstructure. In situ measurements of the acoustic emission (AE) during tensile testing of these materials are presented and related to the microstructure of the sample material. The results are discussed with respect to the variations of activated deformation mechanisms and especially twinning during deformation.
Current Opinion in Solid State and Materials Science, 2008
Biodegradable metals are breaking the current paradigm in biomaterial science to develop only cor... more Biodegradable metals are breaking the current paradigm in biomaterial science to develop only corrosion resistant metals. In particular, metals which consist of trace elements existing in the human body are promising candidates for temporary implant materials. These implants would be temporarily needed to provide mechanical support during the healing process of the injured or pathological tissue. Magnesium and its alloys have been investigated recently by many authors as a suitable biodegradable biomaterial. In this investigative review we would like to summarize the latest achievements and comment on the selection and use, test methods and the approaches to develop and produce magnesium alloys that are intended to perform clinically with an appropriate host response.
Advanced Engineering Materials, 2007
Magnesium alloy AX41 has been deformed at elevated temperatures. Stress relaxation tests were per... more Magnesium alloy AX41 has been deformed at elevated temperatures. Stress relaxation tests were performed in order reveal features of the thermally activated dislocation motion. Internal and effective components of the applied stress have been estimated. Apparent activation volume decreases with the increasing effective stress. Estimated values of the activation volume as well as the activation enthalpy indicate that the main thermally activated process is connected with the rapid decrease of the internal stress.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002
Creep experiments were undertaken to determine the potential for using acoustic emission (AE) to ... more Creep experiments were undertaken to determine the potential for using acoustic emission (AE) to monitor the high temperature deformation of an unreinforced AZ91 magnesium alloy and a similar alloy reinforced with short alumina fibers after a conventional T6 heat treatment. Samples of each material were tested to failure and the fracture surfaces of selected specimens were examined using scanning electron
Journal of the Mechanical Behavior of Biomedical Materials, 2012
Mg-Dy alloys have shown to be promising for medical applications. In order to investigate the inf... more Mg-Dy alloys have shown to be promising for medical applications. In order to investigate the influence of ageing treatment on their mechanical and corrosion properties, three Mg-xDy alloys (x=10, 15, 20 wt%) were prepared. Their microstructure, mechanical and corrosion behavior were investigated. The results indicate that ageing at 250 °C has little influence on the mechanical and corrosion properties. In contrast, ageing at 200 °C significantly increases the yield strength, and reduces the ductility. After ageing at 200 °C, the corrosion rate of Mg-20Dy alloy increases largely in 0.9 wt% NaCl solution, but remains unchanged in cell culture medium.
Advanced Engineering Materials, 2000
Skip to Main Content. There will be a release of Wiley Online Library scheduled for Saturday 27th... more Skip to Main Content. There will be a release of Wiley Online Library scheduled for Saturday 27th November 2010. Access to the website will be disrupted as follows: New York 0630 EDT to 0830 EDT; London 1130 GMT to 1330 GMT; Singapore 1930 SGT to 2130 SGT. ...
Advanced Engineering Materials, 2006
Springer Handbook of Condensed Matter and Materials Data, 2005
ABSTRACT
Fundamentals of Magnesium Alloy Metallurgy, 2013
Mathaudhu/Magnesium, 2012
Czechoslovak journal of …, 1999
This paper describes the influence of thermal cycling on the damping behaviour of composites with... more This paper describes the influence of thermal cycling on the damping behaviour of composites with Mg matrix and two contents (26.0 and 34.1 vol.%) of Saffil short fibres. The composites were prepared by squeeze casting. The logarithmic decrement, as a characteristic of the process responsible for the damping behaviour, was measured after ten thermal cycles between room temperature and an upper temperature. The upper temperature was varied within the range from 100 to 450°C.
Materials Science Forum, 2005
ABSTRACT
Journal of the Mechanical Behavior of Biomedical Materials, 2015
ABSTRACT Magnesium alloys are promising candidates for biomedical applications. In this work, inf... more ABSTRACT Magnesium alloys are promising candidates for biomedical applications. In this work, influences of composition and heat treatment on the microstructure, the mechanical properties and the corrosion behavior of Mg-Gd-Ca-Zr alloys as potential biomedical implant candidates were investigated. Mg5Gd phase was observed at the grain boundaries of Mg-10Gd-xCa-0.5Zr (x=0, 0.3, 1.2wt%) alloys. Increase in the Ca content led to the formation of additional Mg2Ca phase. The Ca additions increased both the compressive and the tensile yield strengths, but reduced the ductility and the corrosion resistance in cell culture medium. After solution heat treatment, the Mg5Gd particles dissolved in the Mg matrix. The compressive strength decreased, while the corrosion resistance improved in the solution treated alloys. After ageing at 200°C, metastable β' phase formed on prismatic planes and a new type of basal precipitates have been observed, which improved the compressive and tensile ultimate strength, but decreased the ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.
KAINER:MAGN.ALLOYS APPL. O-BK, 2000
ABSTRACT The object of this paper is to report on thermal fatigue of some very recently developed... more ABSTRACT The object of this paper is to report on thermal fatigue of some very recently developed Mg-based composites. Particularly, the influence of the reinforcement and crystallographic structure of the matrix are analyzed. A similar study of an Al based MMC is reported and the results are compared with those on Mg based MMCs.
Key Engineering Materials, 1997
Materials Science Forum, 2011
Permanent mold casting is a well-established route for casting large magnesium alloys components.... more Permanent mold casting is a well-established route for casting large magnesium alloys components. Casting parameters like superheat, mold temperature, and holding time can often result in inhomogeneous properties, porosity, and segregation problems in the cast part. In order to optimize the casting process, control of the casting parameters including mold temperatures and holding times is essential to promote directional solidification, and ensure defect free homogenous structure. Binary Mg-9wt.%Al and Mg-10wt.%Gd alloys were used to investigate the effect of casting parameters such as melt temperature and holding time on the part macro and microstructure.
Scripta Materialia, 1997
ABSTRACT Many Mg-based metal matrix composites (MMCs) have been developed and manufactured during... more ABSTRACT Many Mg-based metal matrix composites (MMCs) have been developed and manufactured during the last decade as prospective light high-performance constructional materials. When a MMC is submitted to temperature changes (cooling down from the temperature of fabrication, cyclic temperature changes during operation of structural parts) thermal stresses arise at the interfaces owing to a considerable mismatch of the thermal expansion coefficient of the matrix and that of the reinforcement. Even slight temperature changes may produce thermal stresses which exceed the matrix yield stress, consequently, generating new dislocations at the interfaces causing microstructural changes and plastic deformation of the matrix. Long-term exposure may also result in fatigue damage. It is noteworthy that the effect of temperature variations is similar to creep under non-stationary loading conditions. Acoustic emission (AE) has been observed during thermal cycling of Mg based MMCs. Since dislocation motion and microstructural damage are generally accepted to produce AE, it is possible by AE measurements to identify and to characterize the microstructural changes and to correlate them with temperature or other parameters. The dilatometry technique enables the degree of matrix plastic deformation which superposing the thermal expansion to be determined by measuring the shape changes during testing. The combination of both methods yields non-destructively, at any instant of the test, information on the structure and operating processes over the entire volume of the specimen. This can also provide valuable information for subsequent investigations by microscopy or internal friction. The object of this paper is to report on the recently developed, combined AE and dilatometry technique and its application in a structural evolution in Mg-based MMCs subjected to thermal cycling.
JOM, 2007
... Randy S. Beals, Cam Tissington, Xinmin Zhang, Karl Kainer, Joe Petrillo, Mark Verbrugge, and ... more ... Randy S. Beals, Cam Tissington, Xinmin Zhang, Karl Kainer, Joe Petrillo, Mark Verbrugge, and Mihriban Pekguleryuz ... As a focal point of the 2007 TMS Annual Meeting in Orlando, Florida, the TMS Magnesium Committee held its first plenary session with expert representatives ...
Journal of Alloys and Compounds, 2004
The present paper deals with the analysis of the deformation behavior of differently extruded mag... more The present paper deals with the analysis of the deformation behavior of differently extruded magnesium alloys taken from the AZ series. Rods were extruded using indirect and hydrostatic extrusion which results in a different behavior with respect to mechanical properties and microstructure. In situ measurements of the acoustic emission (AE) during tensile testing of these materials are presented and related to the microstructure of the sample material. The results are discussed with respect to the variations of activated deformation mechanisms and especially twinning during deformation.
Current Opinion in Solid State and Materials Science, 2008
Biodegradable metals are breaking the current paradigm in biomaterial science to develop only cor... more Biodegradable metals are breaking the current paradigm in biomaterial science to develop only corrosion resistant metals. In particular, metals which consist of trace elements existing in the human body are promising candidates for temporary implant materials. These implants would be temporarily needed to provide mechanical support during the healing process of the injured or pathological tissue. Magnesium and its alloys have been investigated recently by many authors as a suitable biodegradable biomaterial. In this investigative review we would like to summarize the latest achievements and comment on the selection and use, test methods and the approaches to develop and produce magnesium alloys that are intended to perform clinically with an appropriate host response.
Advanced Engineering Materials, 2007
Magnesium alloy AX41 has been deformed at elevated temperatures. Stress relaxation tests were per... more Magnesium alloy AX41 has been deformed at elevated temperatures. Stress relaxation tests were performed in order reveal features of the thermally activated dislocation motion. Internal and effective components of the applied stress have been estimated. Apparent activation volume decreases with the increasing effective stress. Estimated values of the activation volume as well as the activation enthalpy indicate that the main thermally activated process is connected with the rapid decrease of the internal stress.