The relationship between structural evolution and high energy ball milling duration in tin reinforced Mg alloys

Abstract

In this study, 9 wt% Sn reinforced Mg alloys are produced by high energy ball milling and conventional sintering method. Effect of ball milling time (30 min, 2 h, 4 h, 8 h, and 12 h) on particle and grain morphology is detected by SEM examination. Phase evolution and solid solution mechanism is monitored by XRD analysis. Sintering process is carried out at 400 °C with 2 h sintering duration under Ar atmosphere. Platelet structure in powder morphology is observed up to 4 h ball milling, which is linked with the texture formation on < 002 > direction in hexagonal structure of Mg. This platelet formation is broken into smaller and monodispersed particle morphology with further milling process due to excessive plastic deformation which eventually provide homogenous dispersion of reinforcement element. Furthermore, ball milling process after 4 h triggers solid solution along with formation of intermetallic phase (Mg2Sn) according to crystallographic approach. The highest relative density values is measured in 8 h milling duration. Besides, the highest hardness value is achieved along with proper distribution of reinforcement element in 8 h condition. The hardness values is increased almost 85% comparing with pure ball milled Mg and 74% increment comparing with as cast Mg. The highest elastic modulus values is measured at 8 h milling condition by ultrasound method and this value is found in reasonable range. By introducing 12 h ball milling process, density, hardness and elastic modulus properties of 9 wt% Sn-Mg alloy is diminished because excessive amount of intermetallic phase formation on grain and grain boundaries. Therefore, 8 h high energy ball milling process is chosen the most suitable condition for this materials system to obtain proper powder packing and sinterability along with superior physical and mechanical properties.