Change In Fracture Mode Research Articles

Experimental study on surface integrity and fatigue life of an ultra-high strength steel by the composite strengthening process of pre-torsion and ultrasonic rolling

A new surface modification method, i.e., the composite strengthening process of pre-torsion and ultrasonic rolling, is proposed for surface strengthening of an ultra-high strength steel (45CrNiMoVA). Based on the enhancement of dislocation density in the internal structure of the material by pre-torsion strengthening process and the grain refinement effect of ultrasonic rolling strengthening process, the evolution law of surface integrity and fatigue life of ultra-high strength steel after the composite strengthening process of pre-torsion and ultrasonic rolling were analyzed. The results show that the composite strengthening process has an obvious surface finishing effect, in which ultrasonic rolling plays a key role. The coupling effect of pre-torsion and ultrasonic rolling causes the residual compressive stress in the surface layer of ultra-high strength steel with large amplitude and deep influenced layer. Compared with the ultrasonic rolling process, composite strengthening can produce deeper plastic deformation on the surface of ultra-high strength steel. After composite strengthening, the high cycle fatigue life of the specimens increases greatly, and the torsional fatigue fracture mode changes to quasi-cleavage fracture. In conclusion, the composite strengthening process of pre-torsion and ultrasonic rolling is of great significance to improve the surface integrity and fatigue life of the ultra-high strength steel.

Microstructural evolution and high-temperature deformation mechanism of 4Cr5MoSiV1Ti steel

Hot-working die steel usually withstands complex loading conditions and higher service temperatures, and its mechanical properties will inevitably deteriorate because of dynamic recovery, recrystallization, and plastic deformation of tempered martensite during service. A systematic study was carried out on a newly developed 4Cr5MoSiV1Ti hot working die steel to clarify the related microstructure evolution and deformation mechanism by stretching deformation at different temperatures ranging from room temperature to 640 °C. Results obtained show that the ultimate and yield tensile strength values at room temperature are about 1904 MPa and 1691 MPa, respectively. With increasing testing temperature, the strength decreases, the plasticity increases, and the fracture mode changes from brittle to ductile. All of these are closely related to a combined effect of tempered martensitic dynamic recovery, recrystallization, and secondary phase re-dissolution. Deformation mechanisms change from dislocation slip to rotation or sliding of ferrite with increasing stretching temperature.

MXene reconciles concurrent enhancement of thermal conductivity and mechanical robustness of SiC-based thermal energy storage composites

Latent heat thermal energy storage techniques based on phase change materials (PCMs) play a vital role in efficient and stable utilization of intermittent solar and thermal energy sources. However, low thermal conductivity and poor mechanical strength are daunting bottlenecks of traditional PCMs, inhibiting their wide applications. Here, we successfully enhance both thermal conductivity and mechanical robustness of porous SiC-based composite phase change materials (CPCMs) via doping MXene into SiC skeletons, which are superior to state-of-the-art ceramic CPCMs. The thermal conductivity of MXene-doped CPCMs achieves 15.21 ​W/(m·K) at a porosity of 72.9%, which is 25% higher than that of undoped counterparts. The underlying mechanism lies in that the oxide layer on the surface of MXene melts at a high temperature, filling the gap between SiC grains and optimizing the thermal transport path. Compared with virgin SiC skeletons, the flexural strength and compressive strength of MXene-doped skeletons are enhanced by 20% and 29%, respectively. This is because MXene removed from the oxide layer disperses in the ceramic matrix and improves the mechanical strength of the composite through pull-out, crack deflection and the change of fracture mode. Superior cycle stability and thermal shock resistance are also demonstrated. High thermal conductivity, robust mechanical strength, exceptional stability, and high solar absorptance enable prepared composites to realize high-performance dual-functional thermal and solar energy storage.

New ternary powder metallurgy Ti alloys via eutectoid and isomorphous beta stabilisers additions

A group of new ternary Ti alloys bearing eutectoid and isomorphous beta stabilising elements was created to be manufactured through the conventional powder metallurgy route. The effect of the simultaneous addition of the same amount of Mn and Nb on the manufacturability, properties, and hardening behaviour was investigated. The ternary alloys are composed of the α-Ti and β-Ti phases and have a lamellar microstructure resulting from the slow cooling upon sintering. However, the size of the equiaxed α grains and of the α + β lamellae is monotonically reduced, especially the interlamellar spacing, as the amount of alloying elements increases. Due to their physical properties, Mn enhances and Nb hinders densification during sintering resulting in a decreasing trend of the relative density with the alloying elements content. Consequently, the resistance to plastic deformation increases (UTS, 514–726 MPa), the ductility decreases (elongation, 13.2–2.6%), and the fracture mode changes from intergranular to transgranular. The new ternary alloys share the same hardening mechanism, but the amount of deformation after necking is, generally, higher for lower amounts of Mn and Nb.

Penetration Fracture Mechanism of Tungsten-Fiber-Reinforced Zr-Based Bulk Metallic Glasses Matrix Composite under High-Velocity Impact

In order to adapt to the launch velocity of modern artillery, it is necessary to study the fracture mechanism of the high-velocity penetration of penetrators. Therefore, the penetration fracture mode of tungsten-fiber-reinforced Zr-based bulk metallic glass matrix composite (WF/Zr-MG) rods at a high velocity is studied. An experiment on WF/Zr-MG rods penetrating into rolled homogeneous armor steel (RHA) was carried out at 1470~1650 m/s. The experimental results show that the higher penetration ability of WF/Zr-MG rods not only results from their "self-sharpening" feature, but also due to the fact they have a longer quasi-steady penetration phase than tungsten alloy (WHA) rods. Above 1500 m/s, the penetration fracture mode of the WF/Zr-MG rod is the bending and backflow of tungsten fibers. Our theoretical calculation shows that the deformation mode of the Zr-based bulk metallic glass matrix (Zr-MG) is an important factor affecting the penetration fracture mode of the WF/Zr-MG rod. When the impact velocity increases from 1000 m/s to 1500 m/s, the deformation mode of Zr-MG changes from shear localization to non-Newtonian flow, leading to a change in the penetration fracture mode of the WF/Zr-MG rod from shear fracture to the bending and backflow of tungsten fibers.

Performance improvement of PDC and PDC bits by cryogenic treatment

Polycrystalline diamond compact (PDC) is one of the most widely used cutting tools in the field of oil and gas drilling. In this paper, PDC was cryogenically treated at temperature of around −190 °C and then the mechanical properties such as microhardness, wear ratio, and impact toughness after cryogenic treatment were tested. The morphology, elemental composition and crystal structure of the PDC was investigated by scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-ray diffraction (XRD). Meanwhile, the residual stress of the PCD layer was analyzed using Raman spectroscopy. Untreated and cryogenically treated PDC were respectively fabricated into drill bits and the drilling performance were tested. The results showed that the average microhardness of the PDC after cryogenic treatment was increased by 5.3GPa/10.4%, the maximum wear ratio was increased by 11.8%, and the impact toughness was greatly improved to reach 420 J and increased by 79.4% on average. The average rate of penetration (ROP) of the bit equipped with untreated PDC was 1.03 m/h, while the ROP of the bit equipped with cryogenically treated PDC was 1.56 m/h, increased by 51.4%. Microscopic characterization revealed that the change of fracture mode and the evolution of residual stress in PDC was the main mechanism for the improvement of mechanical properties.

Regulation of performance of laser-welded socket joint of Mo–14Re ultra-high-temperature heat pipe by introducing Ti into both weld and heat affected zone

Fusion welding of molybdenum (Mo) alloys faces problems including grain coarsening and embrittlement, so that the obtained joints have poor mechanical performance. The research took the socket joints of a novel Mo–14Re ultra-high-temperature (UHT) heat pipe as research objects. Pre-heating, titanium (Ti) microalloying and brazing were adopted for coordinated regulation of defects, microstructures, and mechanical performance of joints. Results show that Ti added can be uniformly mixed with metals in the molten pool and solidly dissolved in the matrix to achieve solid-solution strengthening. Ti entering the weld zone distributes on grain boundaries and in grains, thus decreasing the relative content of Mo oxides on the surface of grain boundaries in the meanwhile of grain refinement, playing a role in purifying grain boundaries. Ti alloying in the weld zone to some extent can inhibit occurrence of pore defects and improve the bearing capacity of joints. Moreover, the brazing layer formed in the heat affected zone (HAZ) not only enlarges the bonding and bearing area of joints, but also shifts the position of the stress concentration point of joints from the near weld zone with poor performance to the area with favorable performance much farther from the weld. Under the joint action of Ti microalloying and brazing, the tensile strength of joints is improved from 140.8 to 399.8 MPa. The fracture mode changes from intergranular fracture to transgranular cleavage-like fracture. The research results can promote the development of technologies for manufacturing novel UHT heat pipes and welding Mo–Re alloys.

Microstructure and properties of MgAlCd filler metal scraped brazing AZ31 magnesium alloy joint

In order to simplify the brazing process of magnesium alloy and make the liquid filler metal rapidly wet the base metal, the phase diagram method was used to design the series of Cd22.8Mg9.2Al and Cd26.3Mg15.3Al series filler metal. The brazing of AZ31 magnesium alloy was realized by scraping brazing under the condition of flame heating. The microstructure and phase of the filler metal and brazing seam were analyzed by XRD, SEM, and EDS. The results show that the microstructure of filler metal is composed of CdMg matrix, granular Al12Mg17, and massive (Al) solid solution. The amount of Al12Mg17 and (Al) solid solutions in filler metal increases with the increase of Al content, and the hardness of filler metal also increases. The Al content increases from 9.2 to 15.3%, and Vickers hardness increases from 183.6HV to 252HV. DSC results show that the melting point of filler metal is between 396.1 °C and 401.5 °C. The analysis results of the brazing seam show that the microstructure of the brazing seam is composed of CdMg3 and Al12Mg17. With the increase of Al content in filler metal, the fracture morphology changes from a river like pattern to rock sugar shape, the fracture mode changes from trans-granular fracture to intergranular fracture and the shear strength of joint decreases from 71 MPa to 53 MPa. The main reason for this phenomenon is the increase in the amount and size of the Al12Mg17 phase.

Impact of different Cr contents on microstructural evolution and mechanical behaviour of CoCrxCuFeMnNiV high-entropy alloys

The CoCrxCuFeMnNiV (x = 0, 0.25, 0.5, 0.75, 1) high-entropy alloy was prepared via vacuum arc smelting, and the effect of different Cr contents on the microstructure evolution and mechanical properties of it was evaluated. The results show that the CoCuFeMnNiV alloy is composed of FCC1+FCC2 phases, while Cr-added CoCrxCuFeMnNiV alloy is composed of FCC1+FCC2+sigma phases; moreover, the amount of sigma phase increases with the Cr content. Through calculations, a phase formation criterion suitable for the CoCrxCuFeMnNiV alloy was established. It was observed that adding Cr does not affect the early solidification behaviour of the FCC1 and FCC2 phases; however, it affects the stability of the FCC1 phase and promotes the transformation of this phase into the sigma phase, as well as secondary precipitation of a nanoscale copper-rich phase on this phase. The formation of sigma phase has a significant strengthening effect on the alloy but reduces its plasticity. The CoCr0.5CuFeMnNiV alloy has favourable comprehensive properties; specifically, its yield strength, compressive strength, microhardness, and fracture strain are 820 MPa, 1050 MPa, 320 HV, and 22.5%, respectively. With an increase in Cr content, the alloy fracture mode changes from ductile to brittle.

Borophene reinforcing copper matrix composites: Preparation and mechanical properties

The excellent mechanical properties that combine strength, flexibility and toughness make borophene a highlighted material system for innovative applications of nanoelectronic devices and promising for reinforcing metal matrix composites. However, the experiments have not been reported so far due to the difficulty of macroscale preparation of borophene sheets. Recently, large-scale, free-standing, ultrastable hydrogenated borophene sheets have been synthesized in our group using an in-situ multi-step thermal decomposition method of sodium borohydride. Here, borophene reinforcing copper matrix composites were prepared by in-situ thermal decomposition of sodium borohydride powder in hydrogen rich environment. The corresponding bulk three-dimensional borophene sheets network/copper composites were prepared by spark plasma sintering. The structure of borophene in the samples before and after sintering is well consistent with that of triangular borophene. The mechanical properties of the composites are significantly improved by the introduction of borophene. The yield strength and ultimate tensile strength of the composites are close to the reported highest values of graphene in copper matrix and far beyond those of boron nitride in copper matrix. The change of fracture mode from ductile fracture to brittle fracture is ascribed to the stronger interfacial affinity between borophene and copper compared with that between graphene and copper. This study paves the way for the practical application of borophene in high-performance metal matrix composites.

Room and High Temperature Tensile Responses of Tib2-Graphene Al 7075 Hybrid Composite Processed through Squeeze Casting.

The development of aluminium composite with the inclusion of advanced materials is a continuous research process due to the increasing industrial demand for advanced hybrid materials. To cater for this need, this research work focuses on the development of Al 7075 alloy reinforced with TiB2 and graphene and on the evaluation of its strengthening mechanism. Two different modes of improving the strength of the hybrid composite have been followed; one is by the inclusion of graphene at three levels of 0.1, 0.2 and 0.3%, and another by the processing route, squeeze casting technique by compression of the molten hybrid composite slurry before casting. The microstructure and characterisation of the composite material are examined and analysed with the help of XRD, SEM, EDAX and chemical spectroscopy. A microstructure evaluation is employed to justify the homogenous dispersal and the existence of reinforced particles. A tensile test is conducted at room temperature and high temperature environments to assess the tensile strength. The research outcome affirms that a significant improvement in tensile and hardness has been noted in comparison with base alloy. The fracture-morphology results affirm the change in fracture mode from brittle to ductile when the tensile testing environment changes from room temperature to high temperature. Finally, the dispersion strengthening mechanism is validated with an empirical approach.

High-temperature creep rupture behavior of dissimilar welded joints in martensitic heat resistant steels

The creep rupture behavior and microstructure changes of dissimilar welded joints of two types of martensitic heat resistant steel F92 and Co3W2, under a creep testing of 115–200 MPa and 873–893 K, were investigated. Fracture position and mode change from transgranular ductile fracture in parent F92 to intergranular brittle fracture in the fine grain heat affected zone (type IV cracking) near F92, with the drop of applied stress. Microstructural degradation resulted from creep with respect to dislocation density decrease, precipitates coarsening, dislocation cells, microvoids, macroscopic secondary cracks, and fracture surface morphology are researched based on detailed experimental results. The creep rupture data are analyzed employing Norton’s power law, Monkman–Grant relation, creep damage tolerance, and Larson–Miller parameter. Main creep damage micromechanisms are analyzed with the aid of calculated and experimental data. The extrapolating creep rupture stress for a creep life of 100,000 h are obtained and the influence of stress change and temperature change on creep life are compared in terms of calculated normalized creep life growth rate.

Effect of Ni addition upon microstructure and mechanical properties of hot isostatic pressed 30CrMnSiNi2A ultrahigh strength steel

Hot isostatic pressing is an advanced powder metallurgical technology for the production of complex and special-shaped components made of ultrahigh strength steel. However, due to the low hardenability of 30CrMnSiNi2A steel, it is difficult to achieve the expected martensitic structure in the sintering process. In this study, the hardenability of the alloy is improved by adding Ni into 30CrMnSiNi2A steel powder. The microstructure, tensile properties and fracture behavior of the sintered 30CrMnSiNi2A-xNi steels (x = 0, 1.5 wt%, and 3.0 wt%) are systematically investigated. Experimental results show that with the increase in Ni addition, the matrix structure changes from granular bainite (0 wt% Ni) to lath bainite (1.5 wt% Ni) and lath martensite (3.0 wt% Ni); and the ultimate tensile strength increases from 1312 MPa to 1466 MPa and 1747 MPa. The improvement in strength is mainly related to the solid solution strengthening of C and Ni atoms in the matrix structure. In addition, the increase in dislocation density and grain boundary density in the matrix structure also promotes the improvement in strength, according to the kernel average misorientation and grain boundary analysis of EBSD. After the addition of Ni powder, the fracture mode changes from the transgranular quasi-cleavage to the interparticle debonding. This is mainly due to the increase in the oxide density at the particle boundaries and the matrix strength.

Macro-micro behaviors of Ti–22Al–26Nb alloy during warm tension

In this paper, the plastic flow rules and fracture evolution mechanisms of the nearly O + B2 Ti–22Al–26Nb alloy during warm tension have been studied within a wide temperature range of 20–800 °C. The macro-micro deformation behaviors of the material have been investigated by means of SEM, EBSD and TEM. It is found that the stress-strain curve at 400 °C exhibits serrated patterns, indicating the occurrence of dynamic strain aging at mild temperature. The overall yield strength decreases and the uniform elongation increases with the temperature in general. However, an unexpected peak of yield strength and also an unexpected valley of uniform elongation are exhibited at 600 °C. Additionally, the uniform elongation shows a positive correlation with strain rate at 600 °C. With the comprehensive analyses of fracture surface characteristics, the morphological variation of the constituent phases and the dislocation structure evolution, the causations of the above phenomena are further explained as follows. The B2 phase is mainly responsible for deformation coordination between O laths with the original {110}B2∥(001)O orientation barely changed, and act as a media for propagating localized slip deformation to O grains. The abnormal mechanical responses at 600 °C are mainly attributed to the change of fracture mode caused by the precipitation of fine acicular O grains, while the softening mechanism at 800 °C is mainly dominated by the dynamic globularization of the O phase.

Microstructure and mechanical properties of 3D-printed nano-silica reinforced alumina cores

Ceramic cores are an important component in the preparation of hollow turbine blades for aero-engines. Compared with traditional hot injection technology, 3D printing technology overcomes the disadvantages of a long production cycle and the difficulty in producing highly complex ceramic cores. The ceramic cores of hollow turbine blades require a high bending strength at high temperatures, and nano-mineralizers greatly improve their strength. In this study, nano-silica-reinforced alumina-based ceramic cores were prepared, and the effects of nanopowder content on the microstructure and properties of the ceramic cores were investigated. Alumina-based ceramic cores contained with nano-silica were prepared using the vat photopolymerization 3D printing technique and sintered at 1500 °C. The results showed that the linear shrinkage of ceramic cores first increased and then decreased as the nano-silica powder content increased, and the bending strength showed the same trend. The fracture mode changed from intergranular to transgranular. The open porosity and bulk density fluctuated slightly. The weight loss rate was approximately 20%. When the nano-silica content was 3%, the bending strength reached a maximum of 46.2 MPa and 26.1 MPa at 25 °C and 1500 °C, respectively. The precipitation of the glass phase, change in the fracture mode of the material, pinning crack of nanoparticles, and reduction of fracture energy due to the interlocking of cracks, were the main reasons for material strengthening. The successful preparation of 3D printed nano-silica reinforced alumina-based ceramic cores is expected to promote the preparation of high-performance ceramic cores with complex structures of hollow turbine blades.

Effect of FeNb on microstructure and mechanical properties of Al-Cu-Ni alloy

The present research work deals with the investigation of mechanical properties and microstructure evaluation by particulate reinforcement of ferroniobium (FeNb) into Al-5Cu-2Ni alloy. The two-step stir casting method was employed for the fabrication of the material. The metallography study was carried out with optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD). The XRD peaks revealed the presence of the Fe2Nb phase and intermetallic compound phases of Al2Cu and Al3Ni2. However, the Fe2Nb phase is in the form of short sticks uniformly distributed around the intermetallic compound phases. Tensile strength, microhardness and impact strength were evaluated according to ASTM standards. The average tensile strength and Vickers microhardness of the Al-5Cu-2Ni matrix alloy were 179 MPa and 115 HV respectively. By adding 1%, 3% and 5% of FeNb particulate reinforcement into Al-5Cu-2Ni alloy, the tensile strength could be enhanced to 185, 193 and 207 MPa respectively. The corresponding microhardness values were 130, 132 and 151 HV, respectively. Thus, the addition of 5% ferroniobium particulate reinforcement material could significantly enhance the tensile strength and microhardness of the composites. Fractography revealed that fracture mode changes from ductile to brittle with the reinforcement of FeNb particles. The FeNb particles resist the dislocation movement of the intermetallic compound phases in the composites leading to micro-cracks and subsequent brittle fracture.

A study on fine Nbss/γ-(Nb,X)5Si3 eutectic with significantly improved room-temperature fracture toughness by added ZrB2

Four NbSi based ultrahigh temperature alloys with compositions of Nb-16Si-20Ti-1ZrC-xZrB2 (x = 0, 0.5, 1, 3) (at.%) were prepared by vacuum non-consumable arc melting. The microstructure evolution, fracture toughness, and fracture behavior of four alloys were investigated. Results showed that four alloys consisted of Nbss, γ-(Nb,X)5Si3, and (Nb,X)3Si phases. The low content of ZrB2 facilitates the disintegration of (Nb,X)3Si, while the high content of ZrB2 stabilizes (Nb,X)3Si. The maze-like Nbss/γ-(Nb,X)5Si3 eutectic structure forms in Nb-16Si-20Ti-1ZrC-0.5ZrB2 alloy. With the increase of ZrB2 content, the room-temperature fracture toughness of Nb-Si-Ti-ZrC-based alloy increases and decreases. When the addition amount of ZrB2 is 0.5 at.%, the room-temperature fracture toughness is the largest of 18.4 MPa·m1/2, and the fracture mode changes from quasi-cleavage fracture to dimple fracture. Compared with the base alloy, it is increased by 28%. It is the highest value of as-cast arc melting that has been reported so far. The maze-like eutectic of the high content of Nbss (54.9 ± 5.9%) phase promotes the formation of microcracks and inhibits the propagation of cracks in Nb-16Si-20Ti-1ZrC-0.5ZrB2 alloy.

Effect of phosphorus segregation on carbides and creep damage of Ni–Fe-based GH984G alloy

The effect of phosphorus segregation on carbides and creep damage of Ni–Fe based GH984G alloy, for the application of advanced ultra-super critical (A-USC) power plant, were investigated under the creep condition of 750 °C and 200 MPa. The results indicate that the primary precipitates of GH984G alloy are MC, M23C6 and γ′ after standard heat treatment. P-doping has no effect on the grain size, γ′ size and morphology. Nevertheless, P atoms segregate at the grain boundaries and around the MC carbides, resulting in a change in the morphology of M23C6 carbides at grain boundary from film-like to granular and a decrease in the density and area percentage of MC carbides. The creep behavior of GH984G alloy at 750 °C/200 MPa changes significantly after P doping and the creep properties (creep life and elongation) are optimized with the increasing P content. The damage feature is microcrack at grain boundaries for P-free alloy, while the creep cavities in P-doped alloy. The fracture mode changes from intergranular fracture to transgranular fracture with the increasing P doping for GH984G alloy after creep at 750 °C/200 MPa. The optimizing of creep properties and transformation of fracture mode of GH984G alloys after P doping are mainly attributed to increase of grain boundary cohesion and the change of carbides caused by the P segregation behaviors during creep process.

Numerical Simulation Study of Expanding Fracture of 45 Steel Cylindrical Shell under Different Detonation Pressure.

Detonation and fragmentation of ductile cylindrical metal shells is a complicated physical phenomenon of material and structural fracture under a high strain rate and high-speed impact. In this article, the smoothed particle hydrodynamics (SPH) numerical model is adopted to study this problem. The model’s reliability is initially tested by comparing the simulation findings with experimental data, and it shows that different fracture modes of cylindrical shells can be obtained by using the same model with a unified constitutive model and failure parameters. By using this model to analyze the explosive fracture process of the cylindrical shells at various detonation pressures, it shows that when the detonation pressure decreases, the cylindrical metal shell fracture changes from a pure shear to tensile–shear mixed fracture. When the detonation pressure is above 31 GPA, a pure shear fracture appears in the shell during the loading stage of shell expansion, and the crack has an angle of 45° or 135° from the radial direction. When the pressure is reduced to 23 GPA, the fracture mode changes to tension–shear mixing, and the proportion of tensile cracks is about one-sixth of the shell fracture. With the explosion pressure reduced to 13 GPA, the proportion of tensile cracks is increased to about one-half of the shell fracture. Finally, the failure mechanism of the different fracture modes was analyzed under different detonation pressures by studying the stress and strain curves in the shells.

Evaluating low cycle fatigue property of nanoscale ZrO2 particles strengthening molybdenum alloy

Dispersion strengthened molybdenum alloys with different nano-size ZrO2 content were prepared by liquid-liquid doping method. The effect of ZrO2 on the microstructure and low cycle fatigue properties of Mo alloys after vacuum annealing was studied, and the relationship between fracture mode, strain amplitude and life was analyzed. The results show that ZrO2 can dreamily refine grains size of Mo alloy. The grain size of Mo-1.2% ZrO2 alloy is reduced to about 3 μm compared with 114 μm of pure Mo. As a result, the yield strength of Mo–ZrO2 alloys was significantly improved. The yield strength of Mo-1.2% ZrO2 alloy is 29.9% higher than that of Mo alloy. The main reason is the dispersion strengthening and dislocation pinning effect of intra-granular ZrO2 on molybdenum alloy. ZrO2 has a remarkable influence on the fatigue properties of Mo alloy. When the content of ZrO2 is 1.2%, and molybdenum alloy has good plastic deformation ability, high fatigue strength coefficient and long fatigue life. The fatigue life of Mo-1.2% ZrO2 alloy is 37.6% higher than that of Mo-2.0% ZrO2 alloy when the strain amplifier is 0.5. The fracture mode of molybdenum alloy is related to the content of ZrO2. The content of ZrO2 increases from 1.2% to 2.0%, and the fatigue fracture mode changes from mixed fracture to inter-granular fracture.