Comparative study of microstructure and mechanical properties of Mg/B4C composites: Influence of sintering method and temperature

• Published in: Materials chemistry and physics Vol. 327; p. 129876
• Main Authors: Ghasali, Ehsan, Kariminejad, Arash, Raza, Saleem, Orooji, Yasin, Paimard, Giti, babenko, Andrii, Jie, Li, Ebadzadeh, Touradj
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2024
• Subjects: Boron carbide; Magnesium; Microwave; Spark plasma sintering; Microwave; Spark plasma sintering; Magnesium; Boron carbide
• ISSN: 0254-0584
• DOI: 10.1016/j.matchemphys.2024.129876

This present work compares the effect of heating methods including microwave and spark plasma sintering (SPS) process on the microstructure and mechanical properties of Mg–B4C. 5 wt%B4C mixed with Mg powders through high-energy mixer mill for 10 min at ethanol media. After mixing, the green bodies were prepared by uniaxially pressing the mixture. The microwave heating was done at sintering temperatures of 600, 650 and 700 °C without soaking time in graphite bed. While, in the case of SPS, the mixture of the powders was directly inserted into a graphite mold and sintering process was performed at 450 °C with initial and final pressures of 10 and 30 MPa at vacuum condition of 17 Pa, sequentially. The corresponding XRD patterns revealed Mg and B4C crystalline phase alongside the reaction product of MgB2 and also MgO byproduct. The FESEM investigations depict uniform distribution of B4C reinforcements at the Mg matrix. Moreover, increasing microwave sintering temperature led to decreasing pores at the microstructure of the prepared sample. The microstructure of SPSed sample revealed almost full densification compared to that of the microwave processed samples at all the sintering temperatures applied. Also, The XPS results show the presence of Mg, O, C and B elements on the surface of prepared composite, and HRTEM with HAADF-STEM images were obtained to study the interface of matrix and reinforcement. The highest bending strength and Vickers hardness of 116 ± 6 Hv and 231 ± 11 MPa were obtained for SPSed sample as well as for the highest relative density. Although the microwave sample was sintered at 700 °C at low pressure, sintering method demonstrated considerable mechanical properties in comparison to SPSed specimen, indicating a successful preparation method as a low-cost, energy- and time-saving process. •Mg–B4C composites were prepared successfully through microwave and spark plasma sintering.•The nano-sized reaction product can improve mechanical properties of composites.•Microwave sintering as pressure less sintering method showed acceptable properties compare to SPS.