The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the m...The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the material’s strength.The formation mechanism of the dual-precipitates was investigated,and the evolution of precipitate orientation was confirmed.A combined SEM,EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation.The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region.Subsequently,the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates.The TAD sample containing dual-precipitates exhibited a 99.1%increase in TYS,equivalent to an increase of 108 MPa,compared to unregulated samples A.According to Orowan calculations,the theoretical strength increment from the three strengthening mechanisms was 113 MPa,closely matching the experimental increment of 108 MPa.Notably,the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.展开更多
Mahu Sag,located in Junggar Basin,China,is the largest conglomerate oil reservoir in the world(in this paper,conglomerate generally refers to rocks containing gravel,including pebbly sandstone,sand conglomerate,and co...Mahu Sag,located in Junggar Basin,China,is the largest conglomerate oil reservoir in the world(in this paper,conglomerate generally refers to rocks containing gravel,including pebbly sandstone,sand conglomerate,and conglomerate).The reservoir has the characteristics of low porosity and low permeability and needs hydraulic fracturing.The micromechanical properties and rock fracture characteristics are studied to provide a theoretical basis for hydraulic fracturing treatment.In this study,the mechanical properties,micromechanical properties,fracture characteristics,and micromechanical mechanism of conglomerate are studied experimentally.Assuming that the gravel size is constant,conglomerate with the same cementation type has the following rules:When the gravel content(GC)is≤40%,the rock fracture is controlled by Orowan additional stress,and the strength of miscellaneous foundation is the key factor,forming a single fracture with high tortuosity.When the GC is 40%–65%,the GC and cementation strength are the key factors of rock fracture,resulting in the fracture network around the gravel.When the GC is≥65%,the rock fracture is controlled by Hertz contact stress.The GC is the key factor.Surrounding gravel and passing through gravel cracks are developed,resulting in complex fracture network,but the transformation scale of fracture network is small.Through this study,the fracture morphology and key factors of conglomerate fracture are explored,which can provide reference for hydraulic fracturing.展开更多
The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were com...The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.展开更多
基金National Natural Science Foundation of China(52374405)Joint Innovaion Fund Project of Lanzhou Jiaotong University and Corresponding Supporting University(LH2024018)State Key Laboratory Open Project(Q110824Q02001)。
文摘The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the material’s strength.The formation mechanism of the dual-precipitates was investigated,and the evolution of precipitate orientation was confirmed.A combined SEM,EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation.The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region.Subsequently,the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates.The TAD sample containing dual-precipitates exhibited a 99.1%increase in TYS,equivalent to an increase of 108 MPa,compared to unregulated samples A.According to Orowan calculations,the theoretical strength increment from the three strengthening mechanisms was 113 MPa,closely matching the experimental increment of 108 MPa.Notably,the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.
基金supported by the Key R&D Program Project of Xinjiang Uygur Autonomous Region (2024B01013)the National Key Research and Development Program of China (2022YFE0129800).
文摘Mahu Sag,located in Junggar Basin,China,is the largest conglomerate oil reservoir in the world(in this paper,conglomerate generally refers to rocks containing gravel,including pebbly sandstone,sand conglomerate,and conglomerate).The reservoir has the characteristics of low porosity and low permeability and needs hydraulic fracturing.The micromechanical properties and rock fracture characteristics are studied to provide a theoretical basis for hydraulic fracturing treatment.In this study,the mechanical properties,micromechanical properties,fracture characteristics,and micromechanical mechanism of conglomerate are studied experimentally.Assuming that the gravel size is constant,conglomerate with the same cementation type has the following rules:When the gravel content(GC)is≤40%,the rock fracture is controlled by Orowan additional stress,and the strength of miscellaneous foundation is the key factor,forming a single fracture with high tortuosity.When the GC is 40%–65%,the GC and cementation strength are the key factors of rock fracture,resulting in the fracture network around the gravel.When the GC is≥65%,the rock fracture is controlled by Hertz contact stress.The GC is the key factor.Surrounding gravel and passing through gravel cracks are developed,resulting in complex fracture network,but the transformation scale of fracture network is small.Through this study,the fracture morphology and key factors of conglomerate fracture are explored,which can provide reference for hydraulic fracturing.
基金National Natural Science Foundation of China(Nos.52004227,U22A20187,52201106)the China Postdoctoral Science Foundation(No.2020M683240)+1 种基金the Key Area Research and Development Program of Guangdong ProvinceChina(No.2020B090924002)。
文摘The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.
基金National Natural Science Foundation of China(51701079)Doctoral Scientific Research Start-up Foundation from Huaiyin Institute of Technology,Jiangsu,China(Z301B18558)Enterprise-University-Research Institute Collaboration Project of Jiangsu Province(FZ20190349)。
