Enhancement of wettability in AZ91/B_(4)C system by a mechanical purification of liquid alloy  

作　　者：Artur Kudyba Wojciech Polkowski Grzegorz Bruzda Adelajda Polkowska Donatella Giuranno 

机构地区：[1]Łukasiewicz Research Network-Krakow Institute of Technology,Zakopian´ska 73 Str.,30-418 Kraków,Poland [2]National Research Council of Italy,Institute of Condensed Matter Chemistry and Technologies for Energy,Via De Marini 6,16149,Genova,Italy

出　　处：《Journal of Magnesium and Alloys》2022年第11期3133-3142,共10页镁合金学报（英文）

基　　金：the financial support given by the National Science Centre (NCN) in Poland,under the project MINIATURA 2, No. 2018/02/X/ST8/03044 in2019–2020。

摘　　要：Mg-based alloys are potential candidate materials for a fabrication of lightweight boron carbide based composites through a reactive melt infiltration approach. In this paper, the effect of a mechanical purification of molten AZ91 alloy’s surface on its wettability with polycrystalline B_(4)C is experimentally evaluated for the first time. For this purpose, sessile drop experiments were performed under the same operating conditions(700℃/5 min;Ar atmosphere), by using both the classical contact heating(CH) and the improved capillary purification(CP) procedure. It was found that the evolution of contact angle values was strongly influenced by the applied procedure. In particular, by using the classical CH procedure, the presence of a native oxide layer on the metal surface hinders the observations of melting process, resulting in a misleading conclusion that the system is non-wettable. Contrarily, during the wetting test performed by applying the CP procedure, the surface oxide layer was mechanically removed by squeezing the molten AZ91 alloy through a capillary. Accordingly, the oxide-free AZ91 drop with a regular and spherical shape was successfully obtained and dispensed on the B_(4)C substrate. A reliable contact angle value of θ =83° was measured at the AZ91/B_(4)C triple line at 700 ℃, which in turn proves that B_(4)C is wetted by the liquid AZ91 alloy. In contradiction to the literature, these good wetting conditions were assisted by a non-reactive wetting mechanism occurring at the AZ91/B_(4)C interface. To succeed in the fabrication of AZ91/B_(4)C composites by liquid metal infiltration, such experimental observations make it reasonable to expect a spontaneous infiltration process exclusively driven by capillarity, which in turn increases the efficiency of the process by the absence of reaction products that could be a potentially detrimental factor.

关 键 词：AZ91 magnesium alloy Magnesium matrix composites Sessile drop Capillary purification procedure WETTABILITY Contact angle MMCS B_(4)C 

分 类 号：TG146.22[一般工业技术—材料科学与工程]