The Effects of Nb Addition on the Microstructure and Mechanical Properties of Melt Spun Al-7075 Alloy

Abstract

The mechanical properties of the Al-7075 material, which is used in important areas such as automotive, aviation and defense industry, are still being studied by researchers. In this study, the effects of different proportions of Nb additives on the microstructure and mechanical properties of the rapidly solidified Al-7075 alloy was investigated. Rapid solidification processes were carried out with a single roller melt spinner at a disk surface speed of 25 m / s. Microstructure characterization was performed by using a scanning electron microscopy (SEM) and X-ray diffraction. According to the results, the Nb additive significantly increased the micro hardness of the Al-7075 alloy. The microhardness of the sample added with 0.5% by weight of Nb is 0.9 GPa. This value is 3 times higher than the sample without Nb added. The Nb contribution has led to modification of the dimensions and shapes of both α-Al and intermetallic phases. Nb addition reduced the average grain size from 9.1 µm to 2.46 µm.

Effects of B Addition on the Microstructure and Microhardness of Melt-Spun Al-7075 Alloy

“…Along with improving the mechanical strength with the aforementioned mechanisms, various researchers are working on adding various impurity elements and/or using new production methods such as rapid solidification techniques in order to modify the microstructure of the Al alloys [9,15,[35][36][37]16,[28][29][30][31][32][33][34]. Various impurity elements as an inoculant agent are used to provide grain refinement and obtain a microstructure having homogeneous distribution and minimum segregation in the Al alloys [38]. In order to refine the grain size in the aluminum alloys, melt inoculation is performed by using mostly aluminum master alloys containing Ti and/or B [39].…”

“…Thanks to the rapid solidification processes, the grain refinement can be effectively triggered by obtaining high-density nuclei in the microstructure of the alloys [4,42,43]. Melt spinning method, which is one of the rapid solidification methods, comes into prominence due to its relatively high cooling rates (10 5 -10 7 K/s) and mass production advantage [38,[42][43][44]. Spraying a homogeneous molten metal alloy onto a rotating copper wheel and rapidly solidifying into a thin ribbon are steps during the process.…”

“…The microstructural and chemical composition differences between rapid solidifying zone and slow solidifying zone in traditional production methods constitute a disadvantage in the alloys. Therefore, in the rapid solidification methods such as the melt spinning process, the entire alloy microstructure solidifies simultaneously and very quickly, which provides a microstructure with homogeneous composition [38]. Additionally, B introduced into the alloy, creates more nucleation sites in the microstructure through the heterogeneous nucleation mechanism together with the rapid solidification process [40] and provides a more homogeneous and finer grained microstructure with the formation of some seconder intermetallic phases [41].…”

Effect of Fe-Ni Substitution in FeNiSiB Soft Magnetic Alloys Produced by Melt Spinning

“…This is due to their disordered and metastable short-range atomic arrangement. In fact, such materials have excellent mechanical and physical properties such as high strength [1], high hardness and superior corrosion resistance [2][3][4][5]. Additionally, iron-nickel based amorphous alloys lacking of crystalline structure exhibit superior soft magnetic properties including high saturation magnetic flux density (Bs), low coercivity (Hc), high magnetic susceptibility (χ) [6].…”

“…Many researchers doing research on the amorphous structures have preferred using the melt spinning method [12,[19][20][21]. It is possible to produce the amorphous and/or nanocrystalline ribbons with a thickness of about 20-50 µm by cooling the molten alloy at cooling rates in range of 10 6 -10 9 K/s with melt spinning process [5]. Molten metal alloy is sprayed onto the surface of rotating cold copper disc and loses its heat rapidly.…”