H.J. Zhang

Influence of pre-deformation on age-hardening response and mechanical properties of extruded Mg–6%Zn–1%Mn alloy

Abstract The effect of cold plastic deformation between solution treatment and artificial aging on the age-hardening response and mechanical properties of alloy was investigated by micro-hardness test, tensile test, optical microscopy (OM) and TEM observation. After solution treatment at 420 °C for 1 h, three kinds of pre-deformation strains, i.e. 0, 5% and 10%, were applied to extruded ZM61 bars. Age-hardening curves show that pre-deformation can significantly accelerate the precipitation kinetics and increase peak-hardness value; however, as pre-deformation strain rises from 5% to 10%, there is no gain in peak hardness value. The room temperature (RT) tensile properties demonstrate that increasing the pre-deformation degree can enhance the yield strength (YS) and ultimate tensile strength (UTS) but moderately reduce elongation (EL); furthermore, the enhancement of YS is larger than that of UTS. No twin can be observed in 5% pre-deformed microstructure; however, a large number of twins are activated after 10% pre-deformation. The peak-aged TEM microstructure shows that pre-deformation can increase the number density of rod-shaped β 1 ′ precipitates which play a key role in strengthening ZM61 alloy.

Enhanced plasticity of Fe-based bulk metallic glass by tailoring microstructure

Abstract The room temperature compressive plasticity of Fe 75 Mo 5 P 10 C 8.3 B 1.7 bulk metallic glass (BMG) was improved from 0.5% to 1.8% by increasing the sample diameter from 1.5 mm to 2.0 mm. With increasing the sample diameter to 2.0 mm, a heterogeneous microstructure with in-situ formed α-Fe dendrite sparsely distributed in the amorphous matrix can be attained. This heterogeneous microstructure is conceived to be highly responsible for the enhanced global plasticity in this marginal Fe-based BMG.

Statistical Analysis on the Mechanical Properties of Magnesium Alloys

Knowledge of statistical characteristics of mechanical properties is very important for the practical application of structural materials. Unfortunately, the scatter characteristics of magnesium alloys for mechanical performance remain poorly understood until now. In this study, the mechanical reliability of magnesium alloys is systematically estimated using Weibull statistical analysis. Interestingly, the Weibull modulus, m, of strength for magnesium alloys is as high as that for aluminum and steels, confirming the very high reliability of magnesium alloys. The high predictability in the tensile strength of magnesium alloys represents the capability of preventing catastrophic premature failure during service, which is essential for safety and reliability assessment.