Effect of milling time on the first hydrogen absorption/desorption curves and structural properties of a MmNi5-Ni alloy obtained by mechanical milling

M.R. ESQUIVEL; G. MEYER

Santiago- Chile

Congreso; JORNADAS CONAMET/SAM 2006; 2006

Universidad de Chile

Mechanical milling has become one of the most successful methods for synthesis of alloys. Easy scaling up and low processing cost are mentioned as main advantages over both full equilibrium and chemical synthesis methods. This technique is specially appropriated to obtain alloys used to interact with hydrogen because it produces defects and strain in the alloy microstructure that enhances the reaction. Nevertheless, the effects of mechanical milling on both the microstructure and hydrogen interaction properties on most hydride forming materials are not completely understood. In this work, the effect of mechanical milling on both the structural properties and first hydrogen absorption – desorption curves of a MmNi5-Ni mixture is analyzed. Mixtures of both Mm (Mischmetal, a lanthanides alloy)-Ni and a MmNi5-Ni were treated in a Uni-Ball-II apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Mixtures of both Mm (Mischmetal, a lanthanides alloy)-Ni and a MmNi5-Ni were treated in a Uni-Ball-II apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. 5-Ni mixture is analyzed. Mixtures of both Mm (Mischmetal, a lanthanides alloy)-Ni and a MmNi5-Ni were treated in a Uni-Ball-II apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. 5-Ni were treated in a Uni-Ball-II apparatus. The chamber was opened at fixed milling times and samples were withdrawn in a glove box under Ar atmosphere. O2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. 2 level was maintained below a 5 ppm level to avoid sample oxidation. Hydrogen-alloy interaction was characterized using a Sievert´s type equipment designed in our laboratory. Absorption – desorption curves were obtained at room temperature, 50 ºC and 90 ºC for samples milled during different periods of time. From these curves, the effect of milling is studied. Scanning electron microscopy (SEM) was used to study the particle size and morphology changes during the evolution of mechanical milling. Phase identity, crystallite size and strain of both MmNi5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation. 5 and Ni were studied using X-ray diffraction (XRD). These changes on structural parameters were correlated to the effect of milling time and governing mechanisms during mechanical milling. Results from hydriding – dehydriding curves were also correlated to changes on microstructure during sample preparation.