In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent th...In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.U2241232,U2341253 and 52375317)the National Key R&D Program of China(No.2022YFB3404204).
文摘In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.
文摘格陵兰冰盖物质平衡由其触地线处冰通量和表面物质平衡组成,表面物质平衡是冰盖表面物质收入和支出的净值,在近期格陵兰冰盖物质损失中占主导地位。本文基于荷兰皇家气象研究院开发的1 km区域气候模式RACMO2.3 p2日表面物质平衡数据,对1958-2022年格陵兰冰盖的表面物质平衡及其组分做了详细分析。结果表明,(1)格陵兰冰盖多年平均表面物质平衡为366.8 Gt·a^(-1),表面物质平衡区域差异明显,冰盖西侧中部为主要强消融区域(表面物质平衡<-1600 mm w.e.·a^(-1)),冰盖东南部的高降水特征导致此处积累区表现为高物质累积态,积累区下部年表面物质平衡超过3200 mm w.e.·a^(-1);(2)季节上,格陵兰冰盖表面物质平衡在冰盖尺度上夏季以负平衡为主,冬季以降水积累为主,呈现从沿海到内陆、从南到北递减的格局;其主要消融季从5月开始,7月达到顶峰(表面物质平衡为-123.8 Gt);(3)近60年来格陵兰冰盖表面物质平衡年际变化大,整体上,20世纪90年代之前,降水主导了表面物质平衡变化,20世纪90年代后,表面物质平衡的显著负趋势(-48.7 Gt·(10 a)^(-2),p<0.05)则由融水径流的快速增加所致;(4)空间上,由表面消融增加和再冻结能力下降导致的冰盖消融区普遍呈现负趋势(<-80 mm w.e.·(10 a)^(-2),p<0.05),冰盖东南部的表面物质平衡变化主要受降水变化驱动。格陵兰冰盖表面物质平衡受大气环流异常、辐射、反照率、海洋等因素影响,未来变暖背景下,冰盖表面物质平衡负趋势更为显著,并诱发海平面上升。
