Good Compressive Properties Research Articles

Multifunctional conductive SA/ATO@TiO2 whisker aerogels for piezoresistive pressure sensor application

Ultralight and flexible aerogel sensors have garnered significant interest, yet challenges persist in developing their high elasticity and exceptional piezoresistive properties. In this work, laminated porous composite aerogels have been successfully prepared by a composite of sodium alginate (SA) and antimony-doped SnO2 coated titanium dioxide whiskers (ATO@TiO2) via directional freezing technique. The resulting SA and ATO@TiO2 (SAT) aerogels with laminated porous structure demonstrate lightweight with low-density (0.06 g·cm−3), good compressive properties, superplastic, and conductive properties. The incorporation of small amounts of rod-like ATO@TiO2 whiskers into SAT aerogels not only enhances its electrical conductivity and thermal insulation, but also imparts a light-colored appearance to the aerogel. The assembled SAT aerogel sensors exhibit high sensitivity within 1.0 kPa (225 kPa−1, 17.86 kPa−1) and maintains excellent fatigue resistance even over 1000 cycles. The temperature-responsive properties of SAT aerogel sensors presented superior thermal insulation properties, and it can operate properly even at a high temperature of 100 °C. More importantly, SAT piezoresistive sensors facilitated real-time monitoring and human-computer interactive activities related to human movement and health, showcasing significant potential in diverse fields.

Butane Tetracarboxylic Acid Grafted on Polymeric Nanofibrous Aerogels for Highly Efficient Protein Absorption and Separation.

Developing high-performance and low-cost protein purification materials is of great importance to meet the demands for highly purified proteins in biotechnological industries. Herein, a facile strategy was developed to design and construct high-efficiency protein absorption and separation media by combining aerogels' molding techniques and impregnation processes. Poly (ethylene-co-vinyl alcohol) (EVOH) nanofibrous aerogels (NFAs) were modified by grafting butane tetracarboxylic acid (BTCA) over them in situ. This modification was carried out using polyphosphoric acid as a catalyst. The resulting EVOH/BTCA NFAs exhibited favorable comprehensive properties. Benefiting from the highly interconnected porous structure, good underwater compressive properties, and abundant absorption ligands, the obtained EVOH/BTCA NFAs possessed a high static absorption capacity of 1082.13 mg/g to lysozyme and a short absorption equilibrium time of about 6 h. A high saturated dynamic absorption capacity for lysozyme (716.85 mg/g) was also realized solely by gravity. Furthermore, EVOH/BTCA NFAs displayed excellent reusability, good acid and alkaline resistance, and unique absorption selectivity performance. The successful synthesis of such aerogels can provide a potential candidate for next-generation protein absorbents for bio-separation and purification engineering.

Polyacrylamide/sodium alginate/sodium chloride photochromic hydrogel with high conductivity, anti-freezing property and fast response for information storage and electronic skin

Photochromic hydrogels have promising prospects in areas such as wearable device, information encryption technology, optoelectronic display technology, and electronic skin. However, there are strict requirements for the properties of photochromic hydrogels in practical engineering applications, especially in some extreme application environments. The preparation of photochromic hydrogels with high transparency, high toughness, fast response, colour reversibility, excellent electrical conductivity, and anti-freezing property remains a challenge. In this study, a novel photochromic hydrogel (PAAm/SA/NaCl-Mo7) was prepared by loading ammonium molybdate (Mo7) and sodium chloride (NaCl) into a dual-network hydrogel of polyacrylamide (PAAm) and sodium alginate (SA) using a simple one-pot method. PAAm/SA/NaCl-Mo7 hydrogel has excellent conductivity (175.9 S/cm), water retention capacity and anti-freezing properties, which can work normally at a low temperature of −28.4 °C. In addition, the prepared PAAm/SA/NaCl-Mo7 hydrogel exhibits fast response (<15 s), high transparency (>70 %), good toughness (maximum elongation up to 1500 %), good cyclic compression properties at high compressive strains (60 %), good biocompatibility (78.5 %), stable reversible discolouration and excellent sensing properties, which can be used for photoelectric display, information storage and motion monitoring. This work provides a new inspiration for the development of flexible electronic skin devices.

Friction Characteristics and Lubrication Properties of Spherical Hinge Structure of Swivel Bridge

A spherical hinge structure is a key swivel bridge element that must be considered when evaluating friction characteristics and lubrication properties to meet the rotation requirement. Polytetrafluoroethylene (PTFE)-based spherical hinge sliders and lubrication coating have been employed for over 20 years, but with the growing tonnage of swivel bridge construction, their capacity to accommodate the required lubrication properties can be exceeded. In this manuscript, the optimal friction coefficient of the spherical hinge is obtained through the finite element analysis method. Four lubrication coatings and four spherical hinge sliders are prepared and tested through a self-developed rotation friction coefficient test, four-ball machine test, dynamic shear rheological test, and compression and shear performance test to evaluate the lubrication and friction properties of the spherical hinge structure. The results of the finite element analysis show that the optimum rotation friction coefficient of the spherical hinge structure is 0.031–1.131. The test results illustrate that the friction coefficient, wear scar diameter, maximum non-seize load, phase transition point, and thixotropic ring area of graphene lubrication coating are 0.065, 0.79 mm, 426 N, 14.6%, and 64,878 Pa/s. The graphene lubrication coating has different degrees of improvement compared with conventional polytetrafluoroethylene lubrication coating, showing more excellent lubrication properties, bearing capacity, thixotropy, and structural strength. Compressive and shear tests demonstrate that polyether ether ketone (PEEK) has good compressive and shear mechanical properties. The maximum compressive stress of PEEK is 87.7% higher than conventional PTFE, and the shear strength of PEEK is 6.07 times higher than that of PTFE. The research results can provide significantly greater wear resistance and a lower friction coefficient of the spherical hinge structure, leading to lower traction energy consumption and ensuring smooth and precise bridge rotation.

Axial crushing responses and energy absorption characteristics of aluminum honeycombs filled with graphene oxide modified rigid polyurethane foam

This study aims to explore the potential application of hollow glass beads (HGB) compounded with graphene oxide (GO, HGB@GO) to improve the mechanical properties of rigid polyurethane foam (RPUF). This HGB@GO/RPUF composite is considered a potential filler for reinforcing aluminum honeycomb (AH). A characterization of the chemical structure and surface morphology of HGB@GO was conducted, as well as the analysis of its effect on the compression properties of the foam. The compressive strength of HGB@GO/RPUF (4 wt. %) is 146.17% higher than that of pure RPUF. This study also compared the deformation modes of AH and foam-filled honeycomb (F-AH) structure under axial crushing. The interaction effects between the foam and AH were also analyzed. The results indicated that the RPUF improves the compressive capacity and deformation stability of the AH through its good compression properties and interaction with the aluminum foil. The use of HGB@GO/RPUF further enhances the energy absorption characteristics of the F-AH. In comparison with the pure RPUF-AH, the total and specific energy absorption of the HGB@GO/RPUF (4 wt. %)-AH increase by 74.65% and 44.98%, respectively. This work demonstrates that the prepared HGB@GO can enhance the mechanical properties of RPUF, and HGB@GO/RPUF-AH is expected to be a desirable energy-absorbing device.

Compressive Property of Biomass Briquettes Made of Hazelnut Shell and Peanut Shell

In Indonesia, energy consumption increases as with its population, while fossil energy sources keep running out. This condition forces the development of non-fossil energy sources. One promising alternative is biomass briquette. In this study a biomass briquette was made using hazelnut shell (limbah cangkang kemiri CK) and peanut shell waste (kulit kacang tanah KT) with various CK concentrations: 0/24, 4/24, 8/24, 12/24, 16/24, 20/24, and 24/24 (w/w). Initially, dried CK and KT waste were processed into charcoal powder with a particle size of ~ 0,25 mm. The briquette was prepared by densification of the two charcoal mixtures at a pressure of 29778,99 N/m2 for 15 min, followed by heating at 60 °C for 4 h. Due to storage and delivery process in the application, briquettes must have good compressive properties. In this study, compressive property of the produced briquette was characterized using a universal testing machine (UTM). The results showed that the values of ultimate strength, modulus of elasticity, and elongation at break of the CK-KT briquette increased with increasing CK concentration, with highest values of 5.69 MPa, 80 MPa and 0.146, respectively.

Construction and tribological properties of poly acrylic acid‐poly(3‐(methacryloylamino)propyl) dimethyl(3‐sulfopropyl)ammonium hydroxide hydrogel coatings embedded with SiO2 nanoparticles on Ti6Al4V substrate

AbstractThe development of highly effective bio‐lubricant coatings for arthritis treatment is extremely demanded. Herein, inspired by the efficient lubrication of articular cartilage, acrylic acid (AA) with (3‐(methacryloylamino) propyl) dimethyl (3‐sulfopropyl) ammonium hydroxide (MPDSAH) hydrogel coatings containing nanoparticles on Ti6Al4V substrate were designed and fabricated via UV grafting technology. SiO2 and SiO2 grafted with PAA polymer brushes (SiO2‐g‐PAA) were separately doped into the PAA‐PMPDSAH hydrogel. The PAA‐PMPDSAH/SiO2‐g‐PAA exhibits good tensile and compressive properties compared with PAA‐PMPDSAH/SiO2 hydrogel, with an enhancement of 183.4% in tensile modulus and 60.8% in compressive modulus. The PAA‐PMPDSAH/SiO2‐g‐PAA hydrogel coatings exhibit a low wear volume, 2.9 ± 0.16 × 106 μm3, representing a decline of 32.1% and 61.3% compared with the PAA‐PMPDSAH and PAA‐PMPDSAH/SiO2 hydrogel coatings, respectively. The antiwear performance has obviously improved. The hydrophilic PAA polymer brushes prevent the agglomeration of nanoparticles and promote homogeneously dispersion within the hydrogel. The three‐dimensional crosslinked network structure of hydrogel effectively protects the structural integrity of the polymer brushes, thereby facilitating enduring lubrication properties. This work provides a strategy for promising artificial joint lubrication in biomedical fields.

Biomimetic Bouligand chiral fibers array enables strong and superelastic ceramic aerogels

Ceramic aerogels are often used when thermal insulation materials are desired; however, they are still plagued by poor mechanical stability under thermal shock. Here, inspired by the dactyl clubs of mantis shrimp found in nature, which form by directed assembly into hierarchical, chiral and Bouligand (twisted plywood) structure exhibiting superior mechanical properties, we present a compositional and structural engineering strategy to develop strong, superelastic and fatigue resistance ceramic aerogels with chiral fibers array resembling Bouligand architecture. Benefiting from the stress dissipation, crack torsion and mechanical reinforcement of micro-/nano-scale Bouligand array, the tensile strength of these aerogels (170.38 MPa) is between one and two orders of magnitude greater than that of state-of-the-art nanofibrous aerogels. In addition, the developed aerogels feature low density and thermal conductivity, good compressive properties with rapid recovery from 80 % strain, and thermal stability up to 1200 °C, making them ideal for thermal insulation applications.

Lightweight polyethylene terephthalate bead foams with good interfacial adhesion and thermal insulation performance fabricated by supercritical carbon dioxide secondary foaming strategy

AbstractThis paper reported the novel supercritical carbon dioxide (scCO2) secondary foaming and molding strategy to prepare the thermal‐insulation polyethylene terephthalate (PET) bead foam part with good interfacial adhesion and high expansion ratio. The incorporation of porous structure could effectively enhance the blowing agent solubility and fabricate the system viscosity difference, which contributed to the expansion and further welding of the expanded PET beads. Under the optimum foaming conditions, PET bead foam parts with excellent comprehensive performance were successfully prepared by molding method in the confined space via scCO2 secondary foaming, and the corresponding welding mechanism of PET beads was further investigated. The obtained foam parts possessed good tensile and compressive properties, reaching 1.03 and 1.27 MPa (at 20% strain) respectively. Besides, the foam part exhibited the low thermal conductivity of 0.060 Wm−1 K−1, which confirmed the improvement of thermal insulation performance owing to the high expansion ratio.

Mechanical, Crystallization, Rheological, and Supercritical CO2 Foaming Properties of Polybutylene Succinate Nanocomposites: Impact of Carbon Nanofiber Content.

As a substitute for conventional polymers for the preparation of biodegradable microcellular polymeric foams, polybutylene succinate (PBS) presents one of the most promising alternatives. However, the low melt strength of PBS makes it difficult to produce high-performance microcellular foams. This study aimed to improve the melt strength of PBS and explore the mechanical, thermal, crystalline, rheological, and supercritical CO2 foaming properties of PBS nanocomposites by using carbon nanofibers (CNFs). This study found that nanocomposites containing 7 wt% CNF exhibited the highest tensile strength, Young's modulus, and bending strength. Moreover, the CNF nanofillers were well dispersed in the PBS matrix without significant agglomeration, even at high filler concentrations. Furthermore, the nanocomposites demonstrated improved melting temperature and crystallinity compared with pure PBS. The rheological analysis showed that the addition of CNFs significantly increased PBS viscosity at low frequencies due to the interaction between the PBS molecular chains and CNFs and the entanglement of CNFs, resulting in a more complete physical network formation when the CNF content reached above 3 wt%. During the supercritical CO2 foaming process, the addition of CNFs resulted in increased cell density, smaller cells, and thicker cell walls, with good laps formed between the fibers on the cell walls of nanocomposite foams. Moreover, the electrical conductivity and electromagnetic interference (EMI) shielding properties of the foamed material were studied, and a nanocomposite foam containing 7 wt% CNF showed good electrical conductivity (4.5 × 10-3 S/m) and specific EMI shielding effectiveness (EMI SE) (34.7 dB/g·cm-1). Additionally, the nanocomposite foam with 7 wt% CNF also exhibited good compression properties (21.7 MPa). Overall, this work has successfully developed a high-performance, multifunctional PBS-based nanocomposite foam, making it suitable for applications in various fields.

Construction of multifunctional cellulose nanofibers/reduced graphene oxide carbon aerogels by bidirectional freezing for supercapacitor electrodes and strain sensors

Carbon aerogel is an excellent conductive porous carbon material, but suffers from poor mechanical properties and fatigue resistance, which greatly limits its application as a flexible electronic device. Herein, the cellulose nanofibers/reduced graphene oxide carbon aerogel (BCRCA) with a unique layered structure was prepared by bidirectional freezing technique and thermal annealing. BCRCA's layered structure gives it ultra-low density (3.25 mg/cm3), high specific surface area (159.53 m2/g) and good compression properties (91.3 % stress retention, 100 cycles at 50 % compression). In addition, BCRCA for supercapacitor electrodes has a high specific capacity of 104.3 F g−1 at 0.1 A g−1 and a high capacitance retention rate of 93 % at 5000 cycles at 2 A g−1. Notably, the BCRCA assembled into a wearable strain sensor exhibits a stable current signal for real-time monitoring of finger, wrist, and elbow joint movements. These advantages make BCRCA have broad application prospects in the field of electronic energy storage devices and wearable strain sensors.

Bearing capacities and failure behaviors of bolt fasten wedge (BFW) active joints used in prestressed internal supports

In this paper, the bearing capacities and failure behaviors of bolt-fastened wedge active joints used in prestressed internal supports are studied. A thorough exploration of the design of the bolt-fastened wedge active joint is elaborated, and an overview, working mechanism, stiffness analysis, parameters, and strength checking are provided. Then, loading tests are conducted on four full-scale specimens. One test is an axial compression test, while the other three tests are performed to analyze the long-axis (Y-axis) eccentricity, short-axis (X-axis) eccentricity, and biaxial (XY-axis) eccentricity. The load–displacement curve, load–strain curve, bending moment-rotation curve, and failure mode of each specimen are obtained. The experimental results show that the samples have good compressive properties and bending resistance. The impact of the X-axis and Y-axis eccentricities on the compressive ultimate bearing capacity is investigated, revealing a significant reduction in the former, while the latter has a minimal effect. Under bidirectional eccentricity, the weakening of the axial bending performance is most apparent. Bidirectional eccentric loads lead to a reduction in the yield load and initial compression stiffness to approximately 90% of those observed under unidirectional eccentricity. Finally, a field test is carried out to compare the constructability and load-holding performances of bolt-fastened wedge active joints with those of commonly used steel wedge active joints. It is demonstrated that the bolt-fastened wedge active joint effectively maintains prestress through bolt fastening, substantially enhancing the safety of foundation pit excavation construction.

Numerical parametric evaluation of ultimate resistance of high-strength bolts

High strength bolts are widely used in the engineering field due to their good compressive properties. Accurate assessment of the ultimate capacity performance of high strength bolts under combined loading is essential to ensure the safety of steel structures in the connection zone. Existing studies are not sufficiently clear on the economic and condition-specific limits on the effects of various factors on high-strength bolts under complex stress conditions. In response to these problems, the aim of this paper is to analyse the effects of different factors on the load-bearing performance of high-strength bolts on the basis of numerical simulations. The mesoscale critical plastic strain (MCEPS) method was used on the model fracture and the accuracy of the model evaluation was verified. The effects of grade, type, diameter and bolt hole clearance on the ductile fracture behaviour of high-strength bolts were investigated. It was found that fully threaded bolts and through-hole clearances can mainly affect the load-bearing properties of high-strength bolts and increase the bolt's fracture-deformation capacity. The load-bearing performance of high-strength bolts under the influence of different factors was also compared with the Eurocode design (EC3) predictions.

Antibacterial, biocompatible, hemostatic, and tissue adhesive hydrogels based on fungal-derived carboxymethyl chitosan-reduced graphene oxide-polydopamine for wound healing applications

In this study, we developed biocompatible, fungus-derived carboxymethyl chitosan (FCMCS)–reduced graphene oxide (rGO)-polydopamine (PDA)-polyacrylamide (PAM) (FC-rGO-PDA) hydrogels with excellent antibacterial, hemostatic, and tissue adhesive properties for wound healing applications. FC-rGO-PDA hydrogels were prepared by the alkali-induced polymerization of DA followed by the incorporation of GO and its reduction during the polymerization AM to form a homogeneously dispersed PAM network structure in FCMCS solution. The formation of rGO was verified using UV–Vis spectra. The physicochemical properties of hydrogels were characterized by FTIR, and SEM, water contact angle measurements, and compressive studies. SEM and contact angle measurements showed that hydrogels were hydrophilic with interconnected pores and a fibrous topology. In addition, hydrogels adhered well to porcine skin with an adhesion strength of 32.6 ± 1.3 kPa, . The hydrogels exhibited viscoelastic, good compressive (77.5 kPa), swelling, and biodegradation properties. An in vitro study using skin fibroblasts and keratinocytes cells showed the hydrogel had good biocompatibility. Testing against two model bacteria, viz. Staphylococcus aureus and E. coli revealed that the FC-rGO-PDA hydrogel has antibacterial activity. Furthermore, the hydrogel exhibited hemostasis properties. Overall, the developed FC-rGO-PDA hydrogel has antibacterial and hemostasis properties, high water holding capacity, and excellent tissue adhesive properties, which make it a promising candidate for wound healing applications.

Physical, Mechanical and Thermal Insulation Properties of Foam Made from Natural Rubber Compounded with Ground Rice Husk

This research attempted to prepare thermal insulation material made of naturally occurring products. Natural rubber (NR) foam comprised of ground rice husk as a filler was practically investigated. STR 5L played as a solid commercial NR was mixed with various chemicals on a two-roll mill. Dicumyl peroxide (DCP) and di-nitroso pentamethylene tetramine (Supercell DPT) were employed as curing and blowing agents, respectively. Physical, mechanical and thermal insulation properties of NR composite foams were studied with various particle sizes (mesh 40 and 60) and quantities (0-80 phr) of the ground rice husk. Cure characterization and preparation of all NR compounds were performed at 160 °C. As a result of tensile properties, the bigger particle size (mesh 40) and the highest amount of the ground rice husk at 80 phr resulted in the maximum tensile strength and elongation at break (%) of the NR composite foams. The thermal insulation property of the NR composite foams carried out by ASTM C177 revealed that the lowest thermal conductivity among three representative NR formulations was found to be 0.0862 W/m.K for the NR foam reinforced with the ground rice husk mesh 40 at 20 phr. Closed cell NR composite foam with a smaller amount of ground rice husk particles provides good compressive strength and heat insulation properties but not good tensile properties.

In-situ synthesis of a FeCoCrNiCu/FeCoCrNiAl composite high entropy alloy coating by laser cladding

FeCoCrNiCu is a face-centered cubic (FCC) high entropy alloy (HEA) with good dislocation storage capacity, ductility, and toughness. FeCoCrNiAl is a body-centered cubic (BCC) HEA whose phase is hard and brittle with high strength and low toughness. In this study, a FeCoCrNiCu/FeCoCrNiAl composite HEA coating was prepared by laser cladding technology. After preparation, the microstructure and mechanical properties of the composite HEA were evaluated. A new two-phase (FCC + BCC) HEA was generated in situ between FCC and BCC HEA, achieving a good transition from hard to soft. The composite coating has the best wear resistance, the friction coefficient is about 0.3, the wear rate is 4.2 × 10−5 mm3/ N·m, and the wear mechanism is abrasive wear. While maintaining high hardness and good wear resistance, the composite coating has good compression properties. The FeCoCrNiCu cladding layer reduced the energy of the FeCoCrNiAl cladding layer by storing dislocations, which reduced its tendency to crack during compression, thus extending the service life of the coating surface.

Effect of Strain Rate on Compressive Properties of Aluminium-Graphene Composites

Graphene-reinforced aluminium composites have been widely studied due to their excellent mechanical properties. However, only a few studies have reported their dynamic compression properties. The purpose of this study is to investigate the quasi-static and dynamic compression properties of graphene-reinforced aluminium composites. The addition of graphene improved the compressive stress resistance and energy absorption capacity of the aluminium matrix. An aluminium-0.5 wt.% graphene composite exhibited good compressive properties due to the different interfacial wave impedance generated by the additional grain boundaries or Aluminium-Graphene interfaces.

The elastic anisotropy, electronic and optical properties of Bi4Si3O12, Bi2SiO5, Bi12SiO20 and Bi2Si3O9 crystals from first-principles calculations

Bismuth silicates are the excellent semiconductor materials with excellent physical and chemical properties. In this paper, the physical properties of four Bi-Si-O crystals such as orhorhombic Bi2SiO5, hexagonal Bi2Si3O9, cubic Bi4Si3O12 and cubic Bi12SiO20 were studied using the first-principles calculations. The research contents include the elastic anisotropy, electronic properties and optical properties of Bi-Si-O crystals. Bi2Si3O9 crystal has the good compressive property. The hexagonal Bi2Si3O9 show the ductile properties, but the other Bi-Si-O materials have the brittle characteristics. In addition, the elastic hardness indicates that all the materials have the relatively low hardness. Their elastic anisotropy was evaluated as follows: orthorhombic Bi2SiO5 > hexagonal Bi2Si3O9 > cubic Bi4Si3O12 > cubic Bi12SiO20. The electronic properties are analyzed in details. The band gap widths of Bi2SiO5, Bi2Si3O9, Bi4Si3O12 and Bi12SiO20 are 2.775 eV, 3.454 eV, 3.997 eV and 2.256 eV respectively. For the static optical anisotropy, the dielectric constants and the related parameters of the above substances are analyzed.

Compressive model and numerical simulation analysis of a low-weight and high-strength structure combined with a buoyancy material and FRP

ABSTRACT The requirements of low weight and high strength are often contradictory in the design and production of manned/unmanned submersibles. In this paper, a novel structure that combines fiber-reinforced composites and buoyancy materials was proposed to solve this contradiction. These two materials in this structure can cooperate and obtain good compressive properties and low densities. A theoretical model of the compressive strength of this combined structure is proposed. Compression experiments were carried out on six groups of samples. The experimental results show that the compressive capacity of the combined structure is greater than the sum of the compressive capacity of buoyancy material and FRP pipe. The stress distribution of the combined structure under uniaxial pressure is simulated through a finite element model. The numerical simulation results and theoretical predictions show good agreement with the experimental data.

The aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered phase at 275°C

ABSTRACT We investigated the aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered (LPSO) phase at 275°C. Its peak hardness is about 116.4 HV after aging for 25 h. We unravelled the evolution of prismatic precipitates through transmission electron microscopy (TEM). The formation process is β′ (10h)→ β′ + β1 (15 h)→ β′ + β1 + β (≥20 h), where nano-scale phase benefits the transformation from β′ phase to β1 phase. In addition to the stable basal LPSO structures, the coexistence and competition balance between the prismatic β′, β1 and β phases synergistically contribute to the high hardness of the aged alloy. The number density of the prismatic precipitates is at the magnitude of 1020/m3. These prismatic precipitates during aging largely determine the hardness of the Mg alloys. The interaction between precipitates and stacking faults brings good compression property.