Ahmed Anwar Qasim, Olasz Dániel, Bobruk Elena V, Valiev Ruslan Z, Chinh Nguyen Q
Department of Materials Physics, Eötvös Loránd University, Pázmány Péter Sétány 1/A, 1117 Budapest, Hungary.
College of Science, University of Kufa, Najaf 54001, Iraq.
Materials (Basel). 2023 Oct 7;16(19):6593. doi: 10.3390/ma16196593.
A supersaturated Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by the equal-channel angular pressing (ECAP) technique at room temperature in order to obtain an ultrafine-grained (UFG) microstructure having an average grain size of about 260 nm. The hardness and microstructural characteristics, such as the phase composition and precipitations of this UFG microstructure were studied using depth-sensing indentation (DSI), transmission electron microscopy (TEM), as well as non-isothermal scanning of differential scanning calorimetry (DSC), and compared to the properties of the un-deformed sample. Emphasis was placed on the effect of the UFG microstructure on the subsequent thermal processes in DSC measurements. It has been shown that the ECAP process resulted in not only an ultrafine-grained but also a strongly precipitated microstructure, leading to a hardness (2115 MPa) two and a half times higher than the initial hardness of the freshly quenched sample. Because of the significant changes in microstructure, ECAP has also a strong effect on the dissolution (endothermic) and precipitation (exothermic) processes during DSC measurements, where the dissolution and precipitation processes were quantitatively characterized by using experimentally determined specific enthalpies, ΔH and activation energies, Q.
为了获得平均晶粒尺寸约为260纳米的超细晶粒（UFG）微观结构，采用等通道转角挤压（ECAP）技术在室温下对一种过饱和的Al-4.8%Zn-1.2%Mg-0.14%Zr（重量百分比）合金进行了加工。使用深度传感压痕（DSI）、透射电子显微镜（TEM）以及差示扫描量热法（DSC）的非等温扫描研究了这种UFG微观结构的硬度和微观结构特征，如相组成和析出物，并与未变形样品的性能进行了比较。重点研究了UFG微观结构对DSC测量中后续热过程的影响。结果表明，ECAP工艺不仅导致了超细晶粒，还导致了强烈析出的微观结构，使硬度（2115兆帕）比新鲜淬火样品的初始硬度高出两倍半。由于微观结构的显著变化，ECAP对DSC测量中的溶解（吸热）和析出（放热）过程也有强烈影响，其中溶解和析出过程通过实验测定的比焓ΔH和活化能Q进行了定量表征。
