In this study ball milling of Al356 and Al2O3 powder mixture was carried out in order to produce Al356-Al2O3 nano-composite containing 20 vol.% Al2O3. The structural evolution and morphological changes of powder parti...In this study ball milling of Al356 and Al2O3 powder mixture was carried out in order to produce Al356-Al2O3 nano-composite containing 20 vol.% Al2O3. The structural evolution and morphological changes of powder particles during ball milling were studied by X-ray diffractometery and scanning electron microscopy analysis. As a result of ball milling Al2O3 particles were uniformly dispersed in Al356 matrix. Furthermore the crystallite size of the Al356 decreased to 25 nm after ball milling for 10 h. Morphological studies of powder particles indicated that the powder particle size continuously decreases with increasing milling time. Hardness and elastic modulus values of powder particles were measured by nanoindentation method. It was found that the hardness and elastic modulus of Al356-20 vol.% Al2O3 nanocomposite were about 216 Hv and 86 GPa, respectively which is higher than 75 Hv and 74 GPa for as-received Al356.展开更多
The nanostructured CoAl intermetallic compound was produced by mechanical alloying （MA） of the Co50Al50 elemental powder mixture in a planetary high energy ball mill. The ordered B2-CoAl structure with the grain siz...The nanostructured CoAl intermetallic compound was produced by mechanical alloying （MA） of the Co50Al50 elemental powder mixture in a planetary high energy ball mill. The ordered B2-CoAl structure with the grain size of about 6 nm was formed via a gradual reaction after 10 h of MA. A thermodynamic analysis of the process was also done. The results showed that the intermetallic compound of CoAl had the minimum Gibbs free energy compared to solid solution and amorphous states indicating the initial MA product was the most stable phase in the Co-Al system which was changed to a partially disordered structure with a steady long-range order of 0.82 at further milling. This amount of disordering caused the enthalpy of final product to show an increase of about 5.1 kJ·mol-1. Calculation of enthalpy related to the triple defect formation revealed that the enthalpy required for Al anti-sites formation was about 3 times greater than that for Co anti-sites formation.展开更多
文摘In this study ball milling of Al356 and Al2O3 powder mixture was carried out in order to produce Al356-Al2O3 nano-composite containing 20 vol.% Al2O3. The structural evolution and morphological changes of powder particles during ball milling were studied by X-ray diffractometery and scanning electron microscopy analysis. As a result of ball milling Al2O3 particles were uniformly dispersed in Al356 matrix. Furthermore the crystallite size of the Al356 decreased to 25 nm after ball milling for 10 h. Morphological studies of powder particles indicated that the powder particle size continuously decreases with increasing milling time. Hardness and elastic modulus values of powder particles were measured by nanoindentation method. It was found that the hardness and elastic modulus of Al356-20 vol.% Al2O3 nanocomposite were about 216 Hv and 86 GPa, respectively which is higher than 75 Hv and 74 GPa for as-received Al356.
文摘The nanostructured CoAl intermetallic compound was produced by mechanical alloying （MA） of the Co50Al50 elemental powder mixture in a planetary high energy ball mill. The ordered B2-CoAl structure with the grain size of about 6 nm was formed via a gradual reaction after 10 h of MA. A thermodynamic analysis of the process was also done. The results showed that the intermetallic compound of CoAl had the minimum Gibbs free energy compared to solid solution and amorphous states indicating the initial MA product was the most stable phase in the Co-Al system which was changed to a partially disordered structure with a steady long-range order of 0.82 at further milling. This amount of disordering caused the enthalpy of final product to show an increase of about 5.1 kJ·mol-1. Calculation of enthalpy related to the triple defect formation revealed that the enthalpy required for Al anti-sites formation was about 3 times greater than that for Co anti-sites formation.
