In the present study,the effects of equal channel angular pressing(ECAP)on the microstructure and mechanical property of the Mg-20Al alloy were systematically investigated.For the first time,the texture of Mg17Al12 ph...In the present study,the effects of equal channel angular pressing(ECAP)on the microstructure and mechanical property of the Mg-20Al alloy were systematically investigated.For the first time,the texture of Mg17Al12 phase and its evolution with ECAP conditions were reported.The results show that increasing the processing temperature and passes generates more uniform distribution and finer size ofβ-Mg17Al12 phases.The large pieces ofβ-Mg17A12 phases are composed of many fine grains with different crystallographic orientations.For theβ-Mg17A12 phase,a preferred distribution of(001)appears at 523 K and 573 K,and hardly varies with temperature.Nevertheless,a random texture is observed at 623 K.The(0002)poles exhibit a preferred distribution at 473 K,but this preferred distribution varies with temperature.A random distribution of(0002)poles is observed when processed at 623 K.Many types of crystallographic planar relationship betweenβ-Mg17A12 phase andα-Mg matrix are observed and the relationships of{11-23}//{100}or{110}or{111}and{1-211}//{100}or//{110}or{111}have a relatively higher frequency than others.The texture ofα-Mg matrix is much different from that of the ECAPed Mg alloys with a relative low Al content,in which a texture with basal poles inclining approximately 45°away from the extrusion direction often develops.The mechanical properties of Mg-20Al alloy are closely related to the temperature and passes of ECAP.A higher temperature often decreases the yield strength,but hardly alters the maximum strength.There is a low plasticity for all the samples and increasing processing temperature slightly enhances the plasticity.The corresponding mechanisms were deeply discussed.展开更多
Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg...Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg17Al12 and the precipitated β-Mg17Al12 phases appeared in the as-cast alloy. The β-Mg17Al12 phase dissolved into α-Mg matrix mostly and the structure kept fine after the optimized homogenization treatment at 380 °C for 15 h. Dynamic recrystallization and consequent grain refinement occurred during extrusion. The banded β-Mg17Al12 precipitates paralleled to the extrusion direction were observed after ageing treatment. The banded precipitation should be attributed to the solidification segregation which was elongated during the subsequent extrusion. Furthermore, the effects of temperature, holding time of homogenization and ageing treatment, and extrusion processing parameters on the microstructural evolution of AZ91 alloy were also discussed in details according to the experimental results.展开更多
基金supported by the Natural Science Foundation of China(51871032)Graduate Research and Innovation Foundation of Chongqing,China(Grant No.CYB17004)+1 种基金Fundamental Research Funds for the Central Universities(2019CDQYCL032)the“111”Project(B16007)by the Ministry of Education。
文摘In the present study,the effects of equal channel angular pressing(ECAP)on the microstructure and mechanical property of the Mg-20Al alloy were systematically investigated.For the first time,the texture of Mg17Al12 phase and its evolution with ECAP conditions were reported.The results show that increasing the processing temperature and passes generates more uniform distribution and finer size ofβ-Mg17Al12 phases.The large pieces ofβ-Mg17A12 phases are composed of many fine grains with different crystallographic orientations.For theβ-Mg17A12 phase,a preferred distribution of(001)appears at 523 K and 573 K,and hardly varies with temperature.Nevertheless,a random texture is observed at 623 K.The(0002)poles exhibit a preferred distribution at 473 K,but this preferred distribution varies with temperature.A random distribution of(0002)poles is observed when processed at 623 K.Many types of crystallographic planar relationship betweenβ-Mg17A12 phase andα-Mg matrix are observed and the relationships of{11-23}//{100}or{110}or{111}and{1-211}//{100}or//{110}or{111}have a relatively higher frequency than others.The texture ofα-Mg matrix is much different from that of the ECAPed Mg alloys with a relative low Al content,in which a texture with basal poles inclining approximately 45°away from the extrusion direction often develops.The mechanical properties of Mg-20Al alloy are closely related to the temperature and passes of ECAP.A higher temperature often decreases the yield strength,but hardly alters the maximum strength.There is a low plasticity for all the samples and increasing processing temperature slightly enhances the plasticity.The corresponding mechanisms were deeply discussed.
基金Project (2011A090200104) supported by Guangdong Science and Technology Special Projects, China
文摘Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg17Al12 and the precipitated β-Mg17Al12 phases appeared in the as-cast alloy. The β-Mg17Al12 phase dissolved into α-Mg matrix mostly and the structure kept fine after the optimized homogenization treatment at 380 °C for 15 h. Dynamic recrystallization and consequent grain refinement occurred during extrusion. The banded β-Mg17Al12 precipitates paralleled to the extrusion direction were observed after ageing treatment. The banded precipitation should be attributed to the solidification segregation which was elongated during the subsequent extrusion. Furthermore, the effects of temperature, holding time of homogenization and ageing treatment, and extrusion processing parameters on the microstructural evolution of AZ91 alloy were also discussed in details according to the experimental results.
