The influence of samarium (Sm) content on the solidification characteristics, microstructure, and mechanical 

properties of Mg–2.8wt%Nd–1.5wt%Gd–0.5wt%Zn–0.5wt%Zr magnesium alloy was studied. The cooling curves and 

microstructure analysis results showed that Sm rare earth element refined the grains of the alloys, where the solidification 

time of α-Mg phase of decreased as addition of Sm, which reflected to the microstructure of alloy and the grains became 

refined, also Sm combined with the initial phase of the intermetallic base alloy and crystallized along the grain boundaries. In 

addition, Mg41Sm5

, Mg3Zn6Sm and (Mg, Zn)3Sm new intermetallic phases were formed as addition of Sm. Both grain 

refinement and formed intermetallic phases led to the improvement in hardness and tensile strength.

The effects of the addition of the rare earth element, erbium (Er), on the microstructure and mechanical

properties of LM 24 alloy were investigated. A microstructural characterisation was performed using an optical 

microscope (OM) and scanning electron microscope (SEM). When 1.0 wt % of Er was added to LM 24 alloy, the mean 

area decreased from 1026.16 µm2

 to 95.35 µ

2

, while the aspect ratio decreased from 3.6329 to 2.322. Observations via 

an optical microscope showed that the unmodified alloy had a coarse plate-like structure. The addition of 1.0 wt % of 

Er produced the best modification effect on the Si phases, which were transformed into fine particles and short rods. 

The mechanical properties with various concentrations of Er were investigated by means of an ultimate tensile test and 

Vicker’s hardness test. The results of the ultimate tensile test showed that the elongation increased with an increase in 

the Er content of up to 0.3 wt %, and then decreased with the addition of more Er. Furthermore, the hardness increased 

slightly with the addition of Er.

This paper describes a standalone hybrid renewable energy system (HRES) design for Al-Faowar village located at West Libya. The hybrid system comprises of Photovoltaic (PV), wind turbines, diesel generators and battery storage system. The system was design the primary load of 170 households, three commercial and government buildings, one school; and one mosque in the village. Numerous combinations of the hybrid system were assessed in HOMER to find the optimal combination based on the Net Present Carbon Dioxide (CO2) emissions. The results of the most optimal hybrid system combinations for Al-Faowar village was 6,000 kW of PV system, 3,750 kW of wind power system, 500 kW of diesel generator and 1,900 Ah of battery storage syste hybrid system in this study shows promising results that capable to meet the load demand via renewable energy generations with minimal diesel generator running time. This paper describes a standalone hybrid renewable energy system (HRES) design for Faowar village located at West Libya. The hybrid system comprises of Photovoltaic (PV), wind turbines, diesel generators and battery storage system. The system was design the primary load of 170 households, three commercial and government buildings, one school; and one mosque in the village. Numerous combinations of the hybrid system were assessed in HOMER to find the optimal combination based on the Net Present Cost (NPC) alongside Carbon Dioxide (CO2) emissions. The results of the most optimal hybrid system Faowar village was 6,000 kW of PV system, 3,750 kW of wind power system, 500 kW of diesel generator and 1,900 Ah of battery storage system hybrid system in this study shows promising results that capable to meet the load demand via renewable energy generations with minimal diesel generator running time.

The effect of the rare earth (RE) element Y on the microstructure and hardness of (Mg–0.5Zn–0.5Zr–2.8Nd –1.5Gd) wt% Mg alloy investigated. 1 wt. % Y was added and compared with the base alloy. The microstructure results show the refinement of the grain by the addition of Y and the grains became smaller about 31.8 % and the volume fraction was increases 11.1% %, which led to the increment of hardness from 48.33 HV (as-cast EV31A) to 53.71 HV (as-cast EV31A +1 Y). Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) results showed that the base alloy mainly contained α-Mg matrix and Mg-(Nd, Gd) as a second phase crystallized along the grain boundaries and addition of (Y) yttrium resulted in the formation of the new phase, Mg-Zn-Y-phase was found as a new ternary phase, where Y combined with the original second phase.

The influence of holmium on the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys 

were investigated. Conventional casting methods are used to produce the alloys. All the results were 

characterized by optical microscopy, scanning electron microscope (SEM) and the Vickers hardness 

test to highlight the influence of holmium addition. The addition of 2.0 wt.% holmium leads to the 

combination of rare earth elements which formed Mg-Zn-Nd-Ho phase. The results have shown the 

addition of Ho improved the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys. By adding 

grain size of 2.0 wt.% holmium had reduced by 18.43%, while the volume fraction increased by 

7.34%. The Vickers hardness value improved 6.18% due to the grain refine and volume fraction 

precipitates. The 2.0 wt.% holmium addition showed a positive result in microstructure and 

hardness value.

The influence of praseodymium (Pr) content on the solidification characteristics, microstructure, and mechanical properties of

ZRE1 magnesium (Mg) cast alloy was investigated. The obtained solidification parameters showed that Pr strongly affected the solidification 

time, leading to refinement of the microstructure of the alloys. When the freezing time was reduced to approximately 52 s, the grain size de-

creased by 12%. Mg12Zn (Ce,Pr) was formed as a new phase upon the addition of Pr and was detected via X-ray diffraction analysis. The ad-

dition of Pr led to a substantial improvement in mechanical properties, which was attributed to the formation of intermetallic compounds; the 

ultimate tensile strength and yield strength increased by approximately 10% and 13%, respectively. Pr addition also refined the microstruc-

ture, and the hardness was recovered. The results herein demonstrate that the mechanical properties of Mg alloys are strongly influenced by 

their microstructure characteristics, including the grain size, volume fraction, and distribution of intermetallic phase