Evolution of iron-rich intermetallics and its effect on the mechanical properties of Al–Cu–Mn–Fe–Si alloys after thermal exposure and high-temperature tensile testing

Si addition is commonly used to modify the iron-rich intermetallics in Al–Cu–Mn–Fe alloys, which is beneficial to increasing the use of recycled aluminum. Most of the available research has focused on the effect of Si content on the room-temperature mechanical properties of Al–Cu–Mn–Fe alloys. To expand the application of Al–Cu–Mn–Fe–Si alloys as light heat-resistant structural components in the automotive and aerospace industries, it is of great importance to investigate the evolution of iron-rich intermetallics and its effect on the fracture behavior of Al–Cu–Mn–Fe–Si alloys after thermal exposure and high-temperature tensile testing. In this work, the evolution of iron-rich intermetallics and the high-temperature mechanical properties of heat-treated Al-6.5Cu-0.6Mn-0.5Fe alloys with different Si contents after thermal exposure and high-temperature tensile testing were assessed by tensile tests, image analysis, scanning electron microscopy, X-Ray diffraction, transmission electron microscopy, and atomic probe tomography. The results indicate that the Al-6.5Cu-0.6Mn-0.5Fe alloys with 0.1Si and 0.5Si additions have excellent and stable high-temperature mechanical properties after long thermal exposure, which are better than those of most heat-resistant Al alloys. The high performance of the high-temperature mechanical properties is attributed to the high heat resistance of secondary intermetallics and precipitated particles. The addition of Si is detrimental to the strength of Al-6.5Cu-0.6Mn-0.5Fe alloys after long thermal exposure. This can be attributed to the solid-state phase transformation of iron-rich intermetallics from α-Fe to β-Fe, which results in the increase of needle-like Fe-rich phases and Si particles, the agglomeration of secondary intermetallics, and the consumption of Al$_{2}$Cu phases

Endophytic fungi from a pharmaceutical plant, Camptotheca acuminata: isolation, identification and bioactivity

About 174 endophytic fungi were isolated from the pharmaceutical plant, Camptotheca acuminata. Of the 18 taxa obtained, non-sporulating fungi (48.9%), Alternaria (12.6%), Phomopsis (6.9%), Sporidesmium (6.3%), Paecilomyces (4.6%) and Fusarium (4.6%) were dominant. ITS rDNA assay indicated that most of the non-sporulating fungi belonged to the Pyrenomycetes and Loculoascomycetes ascomycetes or their anamorph Coelomycetes. The results of the bioactivity test showed that 27.6% of the endophytic fungi displayed inhibition against more than one indicator microorganism. 4.0% and 2.3% of the endophytic fungi showed cytotoxicity and protease inhibition, respectively. The endophytic fungi with bioactivities were distributed in more than 12 taxa including non-sporulating fungi, which are reliable sources for bioactive agents