Changes of microstructure of different quench sensitivity 7,000 aluminum alloy after end quenching

Dry sliding wear tests were performed for 7075 Al alloy under a load of 25-250 N at 25-200°C. The wear behaviors and mechanisms under various testing conditions were explored. A mild-to-severe wear transition is noticed to occur with an increase in the load at 25-200°C. With the temperature increasing, the wear loss decreases constantly under the low load of less than 50 N. It can be suggested that the 7075 Al alloy presents a high wear resistance under a high ambient temperature and low load. Its high wear resistance is found to be attributed to the existence of mechanically mixing layer (MML). The predominant wear mechanism is adhesive and abrasive wear at room temperature. With the ambient temperature and load increasing, oxidative wear and plastic extrusive wear successively prevail due to thermal oxidation and softening of matrix.

Section: Introductionmentioning

confidence: 99%

Dry sliding wear performance of 7075 Al alloy under different temperatures and load conditions

Yang

Sun

et al. 2015

“…The relationship between the internal structure of materials and their properties is the eternal study for the materials science [5][6][7][8]. Therefore, many observation tools, such as scanning electron microscope (SEM) and optical microscope (OM), were developed to perform the characterization of the microstructure in materials.…”

Section: Introductionmentioning

confidence: 99%

X-ray tomography analysis of aluminum alloy powder compaction

Yang

Zhang

2015

Aluminum alloy green compacts obtained by single-action compaction in lubricated and unlubricated dies were investigated by X-ray tomography. For the purpose of obtaining the relationship between the density of green compact and the gray value of reconstructed images, linear fitting was performed. The results show that these data have excellent linear relationship. Then, a new method for analysis of compaction process was presented in this paper. Detailed quantitative analysis of the density and compressive pressure distribution in green compacts was performed. The compressive pressure transmitted ratio and friction index were also discussed. It is found that the lubricated die wall has better effects on the density homogeneity at lower applied compressive pressure. During compaction process, the densification of powder particles in the die mainly occurs in the lower part of the green compact and the factor which mainly influences the friction between die wall and green compact is the applied compressive pressure.

“…Rare earth (RE) elements play an important role in refining grains and reducing defects, finally improving mechanical properties. To date, several RE elements Ce, La, Yb, and Er were added to Al-Cu based alloy, respectively [9][10][11][12]. A well-established finding is that intermetallic compounds (IMCs) formation between rare earth elements and other alloying elements can remarkably improve the tensile strength both at room and elevated temperatures [13].…”

Section: Introductionmentioning

confidence: 99%

Dual characteristic of trace rare earth elements in a commercial casting Al–Cu–X alloy

Hao

Han

2014

The effect of rare earth elements on microstructure and mechanical properties of casting Al-Cu-X alloy (X = Mn, Ti, V, Cd, Zr) was investigated in as-cast and T6 conditions. Microstructure evolution was characterized by optical microscopy, scanning electron microscopy, and transmission electron microscopy. REcontaining intermetallic compounds (IMCs) formed in this alloy were indentified by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). It is shown that the additions of RE (60Ce-40La, wt%) result in the formation of Ce-rich blocky-shaped Al 20 (Ti, V) 2 RE and La-rich skeletal-shaped Al 8 Cu 4 RE. Tensile results of samples after T6 treatment indicate that the strength and ductility increase slightly to 480 MPa and 9.7 %, respectively, with RE content increasing from 0 wt% to 0.3 wt%. This is due to the combinative hardening effects of reduced grain size, enhanced precipitation of h 0 (Al 2 Cu) phase and Al 20 Cu 2 Mn 3 dispersed particles, and minor La-rich IMCs at the grain boundaries of a-Al dendrites. The decrease of strength of 0.5 wt% RE-added sample is ascribed to the aggregation of Al 20 (Ti, V) 2 RE IMCs inside the grains. The dual characteristic of rare earth elements was also discussed in terms of its positive and negative effects on mechanical properties.