Abstract
Dry sliding wear behavior of Mg97Zn1Y2 alloy was investigated at test temperatures of 50–200 °C under three sliding speeds of 0.8 m/s, 3.0 m/s and 4.0 m/s. The wear mechanisms in mild and severe wear regimes were identified by examination of morphologies and compositions of worn surfaces using scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS), and from which wear transition maps under different sliding speeds were constructed on rectangular coordinate systems with applied load versus test temperature axes. It is found that under each sliding speed condition, mild–severe transition load decreases almost linearly within the test temperature range of 50 °C to 200 °C. Microstructure observation and hardness measurement in subsurfaces identify that the softening effect generating form dynamic crystallization (DRX) is the dominant mechanism for the mild–severe wear transition at elevated temperatures. The mild–severe wear transition at 50–200 °C follows the contact surface DRX temperature criterion, and the transition loads can be well evaluated using the criterion.
Highlights
Mg97Zn1Y2 alloy has attracted much attention since a type of high-strength Mg97Zn1Y2 alloy was first prepared by rapidly solidified powder metallurgy (RS/PM) technique in 2011 [1,2,3,4]
The wear rates of the Mg97Zn1Y2 alloy obtained at test temperatures of 50–200 ◦ C under conditions of three sliding speeds are plotted as a function of applied load in Figure 1a–d, respectively
Under the conditions of 3.0 m/s and 4.0 m/s, the dominant wear mechanisms were identified as delamination accompanied by surface oxidation, delamination and delamination + adhesion wear within the mild wear regime, severe plastic deformation, severe plastic deformation + adhesion, and surface melting within the severe wear regime
Summary
Mg97Zn1Y2 alloy has attracted much attention since a type of high-strength Mg97Zn1Y2 alloy was first prepared by rapidly solidified powder metallurgy (RS/PM) technique in 2011 [1,2,3,4]. At room temperature, and yield strength of 510 MPa at 150 ◦ C, which are much superior to the room and elevated-temperature mechanical properties for most of commercial magnesium alloys. As for tribological applications of aluminum and magnesium alloys, the mild–severe wear transition is of great interest to researchers and engineers, since mild wear regime is usually regarded as a safe wear region. Alpas [11], a contact surface dynamic crystallization (DRX) temperature criterion for mild–severe wear transition of magnesium alloys during the room-temperature sliding wear was established in our previous studies, and it has been successfully applied to several magnesium alloys such as AZ31, AZ51, AS31 and Mg97Zn1Y2 alloys [12,13,14,15]. 50–200 ◦ C was assessed by comparing the measured transition loads with the calculated ones using the proposed criterion
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