463 results about "Beta phase" patented technology

A multi-layered ceramic tube having an inner layer of high purity beta phase stoichiometric silicon carbide, a central composite layer of continuous beta phase stoichiometric silicon carbide fibers, and an outer layer of fine-grained silicon carbide. The ceramic tube is particularly suited for use as cladding for a fuel rod used in a power plant or reactor. The ceramic tube has a desirable combination of high initial crack resistance, stiffness, ultimate strength, and impact and thermal shock resistance.

The invention discloses a cast magnesium alloy of low linear shrinkage, which belongs to the field of magnesium alloys. The magnesium alloy consists of Mg, Al, Zn, Mn, rare earth, Nb, Li and M element, wherein the materials have the following weight percentage composition: 1.5-25 percent of Al, 0.1-3.5 percent of Zn, 0.1-2.2 percent of Mn, 0.0002-16 percent of rare earth, 0.0002-4 percent of Nb, 0.0002-9 percent of Li, 0.0002-2 percent of M element and the balance Mg; and the M element is at least one of Zr, Ti, Sr, Ca, C and B. According to the heat-resistant magnesium alloy, the rare earth element and the Nb element are added into the magnesium alloy, so that the structure of beta phase is changed; the Zr element and the M element are added to refine crystal grains; due to combined action of the elements, latent heat of crystallization during alloy solidification is changed; and the magnesium alloy which has superior mold-filling capacity, low shrinkage, superior mechanical property and good machinability, fluidity and die-cast performance and is suitable for casting is obtained.

A coating and process for depositing the coating on a substrate. The coating is a nickel aluminide overlay coating of predominantly the beta (NiAl) and gamma-prime (Ni3Al) intermetallic phases, and is suitable for use as an environmental coating and as a bond coat for a thermal barrier coating (TBC). The coating can be formed by depositing nickel and aluminum in appropriate amounts to yield the desired beta+gamma prime phase content. Alternatively, nickel and aluminum can be deposited so that the aluminum content of the coating exceeds the appropriate amount to yield the desired beta+gamma prime phase content, after which the coating is heat treated to diffuse the excess aluminum from the coating into the substrate to yield the desired beta+gamma prime phase content.

The invention discloses a heatproof magnesium alloy containing Nb, which belongs to the magnesium alloy field. The magnesium alloy is composed of Mg, Al, Si, Mn, rare earth, Nb and M, and comprises the following components by weight: 1.6-9.8% of Al, 0.5-2.5% of Si, 0.05-0.7% of Mn, 0.0001-10% of rare earth, 0.0002-4% of Nb, 0.0001-0.3% of M and the balance of Mg. M element is at least one selected in Ti, Sr, C and B. According to the invention, a rare earth element and an Nb element are added in the magnesium alloy, a structure of a beta phase is changed, thereby the high temperature resistance performance of the magnesium alloy is enhanced, the heatproof magnesium alloy containing Nb has excellent mechanical property and machinery processability, and good fluidity and die casting performance, and is suitable for casting the heatproof magnesium alloy and die casting of the heatproof magnesium alloy.

Certain embodiments of a method for increasing the strength and toughness of a titanium alloy include plastically deforming a titanium alloy at a temperature in an alpha-beta phase field of the titanium alloy to an equivalent plastic deformation of at least a 25% reduction in area. After plastically deforming the titanium alloy in the alpha-beta phase field, the titanium alloy is not heated to or above the beta transus temperature of the titanium alloy. After plastic deformation, the titanium alloy is heat treated at a heat treatment temperature less than or equal to the beta transus temperature minus 20° F. (11.1° C.).

The invention discloses a forging method for a high-microstructure-uniformity titanium alloy cake material. The forging method includes the steps that a titanium alloy casting ingot is subject to high temperature homogenization treatment, one heating number of upsetting pulling forging is carried out after high temperature homogenization treatment is finished, and therefore an original as-cast structure is broken; then a blank is subject to upsetting pulling forging at the temperature higher than the beta phase inversion temperature and lower than the beta phase inversion temperature, and water cooling is carried out after forging is carried out; and finally, the blank is subject to 2-3 heating numbers of upsetting pulling forging at the temperature lower than the beta phase inversion temperature by 30 DEG C to 50 DEG C to mold the cake material with the diameter ranging from 400 mm to 700 mm and the thickness ranging from 100 mm to 200 mm. According to the forging method, the manners of high temperature homogenization treatment, water cooling after forging, reversing upsetting pulling, diagonal line drawing out and the like are matched, reasonable heating and heat preservation coefficients ate reasonably designed, and the uniformity of the blank is guaranteed to the maximum degree; two-phase region high-low-high forging process at the temperature below the beta phase inversion temperature by 30 DEG C to 50 DEG C-50 DEG C to 70 DEG C-30 DEG C to 50 DEG C is adopted, and the problem that single display signals are prone to occurrence during finished product flaw detection is solved.

A method for selectively dissolving the beta (β) phase of a titanium alloy out of the surface of the alloy, thereby leaving behind a nano-scale porous surface having enhanced bonding properties with either a biological tissue, such as bone, or an adhesive material, such as a polymer or ceramic by immersing the alloy in an ionic aqueous solution containing high levels of hydrogen peroxide and then exposing the alloy to an electrochemical voltage process resulting in the selective dissolution of the beta phase to form a nano-topographic metallic surface.

The invention relates to the technical field of ceramic materials, in particular to a silicon nitride ceramic and a preparation method thereof. The preparation method comprises the steps that a rare earth oxide mixture, a beta-phase silicon nitride crystal and a wear-resisting additive are added in an alpha-phase silicon nitride powder, mixing, drying, forming and sintering are carried out, and therefore the silicon nitride ceramic with high tenacity, strength, heat conductive rate and wear resistance is obtained. Due to the fact that the rare earth oxide mixture is added into silicon nitride, the crystal boundary can be effectively weakened, and the silicon nitride ceramic tenacity, strength and heat conductivity are significantly improved; then the beta-phase silicon nitride crystal is added, so that the bimodal distribution structure of silicon nitride crystal particles is obtained at the same time, and the silicon nitride ceramic tenacity, strength and heat conductivity are further improved; the wear-resisting additive is added, so that the silicon nitride ceramic wear resistance is significantly improved, the silicon nitride ceramic tenacity, strength and heat conductivity are not affected, and the silicon nitride ceramic has the high tenacity, strength, heat conductive rate and wear resistance at the same time.

The invention discloses a cast ingot cogging forging technology for improving the structure uniformity of large-thickness forging stocks of titanium alloy. Cogging forging is carried out on the titanium alloy two heating times under the condition of the heating temperature of 1150 DEG C and 1100 DEG C; the titanium alloy is forged at a heating time under the condition of the heating temperature being 20-45 DEG C below the temperature of a beta phase transformation point; the titanium alloy is forged at a heating time under the condition of the heating temperature being 30-80 DEG C above the temperature of the beta phase transformation point; the titanium alloy is forged 2-5 heating times under the condition of the heating temperature being 20-45 DEG C below the temperature of the beta phase transformation point, and then the large-size titanium alloy forging stocks with the even structure are obtained. The cast ingot cogging forging technology is suitable for large cast ingot cogging and forging stock forging of titanium alloy of an alpha type or an alpha-beta type or an approximate-beta type, and requirements for manufacturing of large-size titanium alloy casting pieces or parts which are needed for manufacturing planes and have high requirements for structure temperature uniformity can be met.

The invention relates to a TiAl-intermetallic-compound vacuum diffusing connection method, belonging to the TiAl-intermetallic-compound welding field, which overcomes the technical drawbacks of high temperature of diffusing connection and high pressure of diffusing connection in the prior TiAl-intermetallic-compound diffusing connection technology. The invention adopts hydrogenated titanium or titanium alloy chaff as the interface layer of diffusing connection. Ti3Al+TiAl dual phase (Alpha2+Gamma) organ can be formed under the temperature of diffusing connection titanium, which facilitates the formation of high-intensity connector lug of TiAl-intermetallic-compound diffusing connection. And hydrogen makes the flow stress of thermal deformation of titanium or titanium alloy decrease and the thermal plasticity increase, so that hydrogenated titanium or titanium alloy is prone to deform under high temperature. Meanwhile,, the self-diffusing capacity of hydrogen in titanium or titanium alloy and the diffusing capacity of solute are enhanced, more particularly, in Beta phase the capacities are more enhanced, so that hydrogen can accelerate the diffusing of the alloy elements, reduce the atomic combination energy and the diffusing activation energy, promote the diffusing coordinated deformation capacity, and the reliable diffusing connection of connector lug of TiAl-intermetallic-compound can be realized under comparatively low temperature.

The invention relates to a method for manufacturing a titanium alloy having superelastic properties and / or shape memory for biomedical use, which comprises the steps of: preparing an ingot by melting the various metals that form the desired alloy in a vacuum; optionally homogenising the ingot in a vacuum by high-temperature annealing (higher than 900 DEG C); first quenching; mechanical shaping (rolling, drawing, machining or the like); heat treatment for redissolution in beta phase beyond the beta transus temperature (until a second temperature and then maintaining same for a certain time); and second quenching; characterised in that said heat treatment phase is carried out in a gaseous atmosphere and also constitutes a surface treatment suitable for forming on the surface a layer of nitride, carbonitride, oxide, oxynitride or the like.

The invention discloses high-plasticity two-phase yttrium-containing magnesium-lithium-aluminum alloy and a preparation method thereof. The alloy comprises the following specific components in percentage by weight: 9.50-10.80% of Li, 3.00-5.00% of Al, 0.50-0.70% of Y, 0.10-0.30% of Zr and the balance of Mg; the alloy has the structural characteristics that an alpha phase, a beta phase and a precipitated phase exist at the same time, wherein the alpha phase is a Mg-based solid solution and is in a close-packed hexagonal structure, the beta phase is a Li-based solid solution and is in a body-centered cubic structure, and the precipitated phase is a rare earth compound Al2Y; and the alloy has the characteristics of low density, high plasticity and higher strength. The preparation method disclosed by the invention is a normal-temperature plastic deformation method which combines casting with equal channel angular extrusion or traditional extrusion deformation process; and compared with the traditional high-temperature deformation process, the preparation method has good practicality and is simpler and more convenient to operate, and can be used for effectively lowering the production cost, thus the preparation method has good industrial production prospects.

This invention discloses a beta-type Ti alloy with low elastic modulus for mrdical application. The Ti alloy comprises: Nb 30-37%, Zr 0-20%, and Ti. The cast structure of the Ti alloy is beta phase. The Ti alloy has moderate strength, and can satisfy the strength requirement for clinical bearing material. The elastic modulus of the Ti alloy is only 45-55% that of Ti-6Al-4V alloy. The alloy is a casting alloy, and has no noble metals added such as Ta, thus effectively lowering the cost. Besides, all the added elements have biocompatibility, and toxic elements are avoided. The Ti alloy has high biocompatibility and mechanical compatibility, and can be used to produce bone plates with reduced stress shielding effect.

The high stability and high magnetism quenched R-Fe-B base permanent magnetic alloy powder has the basic expression of RxFe100-x-y-z-vMzCovBy, where R is light RE element(s) Nd, Pr and La, and M is element(s) of Nb, Zr, Ti, etc; and consists of main R2Fe14B phase and small amount of superfine auxiliary Fe-alpha-M-beta phase. Adding Nb and other transition elements to form small amount of superfine auxiliary Fe-alpha-M-beta phase during fast solidification can inhibit over nucleation and growth of Nd2Fe14B crystal grain, improve the performance of the quenched material, fine the Nd2Fe14B crystal grain and raise the temperature stability and antioxidant process of the material. In addition, the permanent magnetic alloy powder has obviously raised intrinsic coercive force, high saturated magnetization, high residual magnetism and other advantages.

The invention relates to a forming method of an alloy comprising predominantly Ti β or nearby β stage, comprising the steps of:Preparation of a homogeneous mixture of particle powder comprising micrometric particles of pure Ti and nanoscale particles of at least one additional element or compound promoting the beta phase of the Ti during its cooling from its phase transition temperature.exposing said particle powder mixture to a focused energy source that is selectively heat at least a portion of a bed of said homogeneous powder mixture at a temperature between 850 and 1850° C. cooling of the part having undergone this exposure with conservation of the phase b of the Ti.

A beta-phase NiAl overlay coating containing a dispersion of ceramic particles and a process for depositing the overlay coating. If the coating is used to adhere a thermal barrier coating (TBC), the TBC exhibits improved spallation resistance as a result of the dispersion of ceramic particles having a dispersion-strengthening effect on the overlay coating. The overlay coating contains at least one reactive element and is deposited so that the some of the reactive element deposits as the ceramic particles dispersed in the overlay coating.

The invention provides a preparation method for a rear-earth magnesium alloy. The preparation method comprises the following steps of: casting a magnesium melt, extruding and forming after solution treatment, then carrying out cold-rolling and ageing treatment to obtain the rear-earth magnesium alloy, wherein the rear-earth magnesium alloy comprises Mg, Nd, Gd, Y, Zn and Zr. Compared with the prior art, cold-rolling and ageing treatment is carried out after carrying out solution treatment, extruding and forming, so that a great number of beta phases and LPSO phases exist on a crystal boundary, the crystal boundary is pinned to prevent crystalline grains from growing in a transformation process, crystalline grains in the alloy are refined, and therefore, yield strength of the rear-earth magnesium alloy is improved; the rear-earth magnesium alloy has the LPSO phases with 14H structures, and is regularly distributed along extruding direction; stability of the boundary improves strength and toughness of the rear-earth magnesium alloy; moreover, high-density dislocation is introduced in cold-rolling, and nucleation of beta' phases in an ageing process is promoted, so that ageing hardening effect of the alloy is improved; meanwhile, the beta' phases can be more refined by the cold-rolling.

The invention relates to a large-scale processing method of Ti-6Al-4V titanium alloy rod bars with the phi of 200-400mm and the length of over 3000mm. The technique is characterized by adopting Ti-6Al-4V titanium alloy casting ingots with the phi of 700-950 mm, a gas furnace for heating and heat preserving at 1150 DEG C, a hydraulic press for hammer cogging, and adopting multi-heating number smithing over the beta transition temperature with the whole smithing ratio not smaller than 3; heating and smithing below the beta transition temperature by 20-30 DEG C with a smithing ratio of 1.5-1.8; preserving the heat for 0.5-3 hours over the beta transition temperature by 20 DEG C, water cooling, performing homogenization treatment; finally heating below the beta transition temperature by 30-50 DEG C, performing multi-heating number smithing in the alpha+beta phase section to the finished product format and the total forging ratio of the alpha+beta phase section being not less than 6. The weight of a single rod bar is greatly improved through integral smithing of casting ingots / large-scale smithing stocks, the length of the rod bar can reach more than 3 m and the rod bars have favorable tissue and performance.

The invention discloses an electrified railroad homo-phase traction power supply system. A traction transformer (SS1) of a traction substation is a three-phase-two-phase transformer; three phases (A, B and C) of the primary side of the traction transformer (SS1) are connected with a public power grid; a voltage reduction transformer (G), a first single-phase current transformer (M1), a direct-current capacitor (C) and a second single-phase current transformer (M2) are connected between an alpha output phase and a beta output phase of the secondary side in turn; the alpha phase supplies power to a locomotive (L), and the output voltage of the alpha phase is 27.5kV; and the output voltage of the beta phase is between 600 and 2,000V. The system can implement two-arm homo-phase power supply of the railroad traction substation without split phase, reduces the split phase link, is favorable for high-speed, stable and safe operation of the railroad, and has the advantages of simple structure, low cost and convenient implementation.

The invention relates to a method for processing TC4 titanium alloy into forged rings, comprising the following steps of: (1) raising the temperature of a titanium cast ingot to 1150-1200 DEG C in a natural gas heating furnace, and keeping the temperature for more than 180 minutes to ensure that the inner temperature and the outer temperature of the whole titanium cast ingot are consistent and uniform; (2) directly processing the titanium cast ingot into a square blank at the deformation rate of 70%-80% by utilizing an oil press; (3) sawing the square blank into small blanks by using a band saw; (4) heating and forging the small blanks for three times by utilizing a resistance heating furnace to form cakes; (5) punching in the centers of the cakes by using a puncher; (6) heating the hollow blanks to 950 DEG C, keeping the temperature for more than120 minutes, and then broaching by using a saddle; and (7) completely annealing at the temperature of 120-200 DEG C by adopting the alpha+beta / beta phase transformation point temperature of 985 DEG C, placing the blanks in the resistance heating furnace at the temperature below 500 DEG C, keeping the temperature of 785 DEG C for 90 minutes, and then cooling in the air. The titanium cast ingot is forged into qualified forged rings by using a reasonable forging process.

The invention relates to high thermal conduction electronic package material. Its components are as follows filling powder 10-80%, epoxy resin 5-30%, curing agent 10-65%, curing accelerating agent 0.1-2.5%, release agent 0.5-3%, colorant 0.5-3%, and proper flame retardant and thixotropic agent. The filling powder can be beta phase silicon nitride powder, or the mixture of the beta phase silicon nitride powder and the silicon dioxide whose adding proportion is 5-95% of the filling total weight. The invention uses beta phase silicon nitride powder as the filling to increase material electrical thermal, property, and mechanical properties, optimize filling powder size distribution to increase package material thermal conductivity and high temperature fluidity, mixes the beta phase silicon nitride powder and silicon dioxide to use as filling to make the package material thermal conductivity and expansion coefficient controllable, and greatly shorten industrialization production transformation period.

A protective coating system includes a nickel-aluminum-zirconium alloy coating having at least one phase selected from gamma phase nickel, gamma prime phase nickel-aluminum, or beta phase nickel-aluminum in combination with the gamma phase nickel or the gamma prime phase nickel-aluminum. For example, the nickel-aluminum-zirconium alloy coating includes about 0.001 wt % to 0.2 wt % zirconium.

Disclosed is a method for manufacturing a tube and a sheet of niobium-containing zirconium alloys for the high burn-up nuclear fuel. The method comprises melting Nb-added zirconium alloy to ingot; forging the ingot at beta phase range; beta-quenching the forged ingot after solution heat-treatment at 1015-1075° C.; hot-working the quenched ingot at 600-650° C.; cold-working the hot-worked ingot in three to five passes, with intermediate vacuum annealing; and final vacuum annealing the cold-worked ingot at 440-600° C., wherein temperatures of intermediate vacuum annealing and final vacuum annealing after beta-quenching are changed so as to attain the condition under which precipitates in the alloy matrix are limited to an average diameter of 80 nm or smaller and the accumulated annealing parameter (SIGMA A) is limited to 1.0x10-18 hr or lower.

The invention relates to an efficient multilayer composite electrode wire, which comprises a core part and a wrapper wrapped on the core part. The electrode wire is characterized in that: the core part is provided with a brass wire core formed by performing diffusion annealing, water cooling and continuous drawing and continuous retracting treatment on a brass core wire, and the metallographic structure of the brass wire core is mainly an alpha-phase structure; and the wrapper is a diffused alloy layer formed by performing diffusion annealing, water cooling and continuous drawing and continuous retracting treatment on a copper metal coating and a zinc metal coating which are sequentially plated on the brass core wire, and the metallographic structure of the diffused alloy layer is mainly a beta-phase structure. The electrode wire is prepared by the following steps of: plating the copper and zinc metal coatings on the core wire, then performing diffusion annealing, water cooling and continuous drawing and continuous retracting treatment, drawing, and thus obtaining the electrode wire. Compared with the prior art, the invention has the advantages that: the cutting efficiency of the efficient multilayer composite electrode wire is remarkably higher than that of a common galvanized wire, the comprehensive cutting cost of the efficient multilayer composite electrode wire is lower than that of the common galvanized wire, and the efficient multilayer composite electrode wire has good universality.

The invention discloses a method for preparing an ultrafine grain titanium alloy by using an alpha'' orthorhombic martensite microstructure. According to the method disclosed by the invention, based on the characteristic that a full alpha'' orthorhombic martensite structure can be obtained by using a double-phase titanium alloy consisting of specific components and having Mo equivalent of 4-8%, and by using a unique texture characteristic of alpha'' orthorhombic martensite, an ultrafine grain double-phase titanium alloy can be prepared by virtue of thermal deformation. The method specifically comprises the following steps: firstly, performing heat treatment on a deformed titanium alloy forging stock or sheared billet at Tbeta-Tbeta+80 DEG C (Tbeta is a beta phase transformation point), and quenching to room temperature to obtain the full alpha'' orthorhombic martensite structure; secondly, forging at Tbeta-(150-300) DEG C, and performing compressional deformation and block cold treatment; and finally, performing relief annealing treatment at 400-500 DEG C to obtain an ultrafine grain double-phase titanium alloy. By adopting the method disclosed by the invention, an ultrafine grain structure of which the average grain size is less than 0.5 micron can be obtained under the condition of small deformation, so that the method is suitable for various plastic deformation manners such as forging and extruding and is simple to operate; requirements can be met by virtue of conventional equipment; and therefore the method has a good application prospect.

One embodiment of a method of refining alpha-phase grain size in an alpha-beta titanium alloy comprises working an alpha-beta titanium alloy at a first working temperature within a first temperature range in the alpha-beta phase field of the alpha-beta titanium alloy. The alloy is slow cooled from the first working temperature. On completion of working at and slow cooling from the first working temperature, the alloy comprises a primary globularized alpha-phase particle microstructure. The alloy is worked at a second working temperature within a second temperature range in the alpha-beta phase field. The second working temperature is lower than the first working temperature. The is worked at a third working temperature in a third temperature range in the alpha-beta phase field. The third working temperature is lower than the second working temperature. After working at the third working temperature, the titanium alloy comprises a desired refined alpha-phase grain size.

The invention belongs to the technical field of photovoltaic grid-connected inverters, and particularly relates to a T-type three-level inverter finite set model prediction control method and system, which have the advantages that the delay time is shortened when rapid dynamic response is ensured and a nonlinear system is introduced. The prediction control method comprises the following steps: the three-phase output of an inverter is grid-connected with a power grid through inductance and resistance loads under the condition that an equation is met, wherein the equation, R and L are respectively an resistance load and an inductance load; u refers to the voltage vector generated by the inverter, e refers to the voltage vector of the power grid, and I refers to current vectors of the loads; a voltage uaN, a voltage ubN and a voltage ucN of output phases of the inverter are converted through Clark, and an abc three-phase static coordinate system is converted into an alpha-phase and a beta-phase static coordinate system.

The invention relates to a wire electrode (1, 1') for electric discharge cutting processes and a method for the production thereof. The wire electrode (1, 1') has a core (2) containing a metal or a metal alloy, and a coating (3, 4; 3, 4, 5) that surrounds the core (2) and includes one or more coating layers (3, 4, 5), at least one (3) of which contains a phase mixture of beta-brass and / or beta'-brass and gamma-brass. In said at least one coating layer (3) containing beta-brass and / or beta'-brass and gamma-brass, the beta-phase and / or beta'-phase and the gamma-phase are arranged next to each other in a fine-grained structure in which the mean size of the beta-brass and / or beta'-brass grains and the gamma-brass grains amounts to a maximum of 5 [mu]m relative to the cross-section extending perpendicular to the longitudinal axis of the wire electrode (1, 1'). In order to produce the wire electrode (1, 1'), a wire is used that has a coating layer predominantly containing gamma-brass, and a homogenizing step is carried out in which the gamma-brass is substantially transformed into a beta-brass having a minimum zinc concentration of 51 percent by weight at temperatures exceeding 600 DEG C, and the wire (1, 1') is finally cooled, a process during which zones of gamma-brass are separated from the supersaturated solid solution of beta-brass.

The invention relates to a thermal treatment process for a TC18 titanium alloy and belongs to the technical field of materials. A method comprises the following steps: preserving heat of the TC18 titanium alloy at the temperature between Tbeta-60 DEG C and Tbeta-100 DEG C (Tbeta is the beta-phase transition temperature of the alloy) for 2-8 hours, and cooling to the room temperature through air cooling or water cooling; aging the alloy at the temperature of 540-600 DEG C for 4-12 hours, and cooling to the room temperature through air cooling. By selecting the heat-preserving temperature, time and cooling way, the microscopic structure of the alloy can be regulated and controlled effectively, a microscopic structure in which an equiaxial phase alpha (the content is higher than 10 percent by volume, and the size is greater than 2 microns), a flaky phase alpha (the thickness is greater than 0.5 micron) as well as a large number of fine needle phase-alpha and phase-beta substrates are matched is realized, the TC18 titanium alloy is high in strength, plasticity and toughness, and the problems of poor alloy strength in a dual annealing process and difficulty in meeting the use requirements on the plasticity and toughness of the alloy in a solid solution-aging process are solved. The method is suitable for industrial application.

The invention discloses a MgAlZn series heat resistant magnesium alloy containing niobium, and belongs to the magnesium alloy field. The magnesium alloy is composed of elements of Mg, Al, Zn, Mn, rare earths, Nb, Zr and M, and comprises, by weight, 1.5 to 2.5 percents of Al, 0.1 to 3.5 percents of Zn, 0.1 to 2.2 percents of Mn, 0.0002 to 16 percents of rare earths, 0.0002 to 4 percents of Nb, 0.001 to 2 percents of Zr, 0.0002 to 2 percents of M element, and the balance Mg; wherein the M element is at least one of Ti, Sr, Ca, C and B. According to the magnesium alloy, the structure of Beta phase is changed and the heat resistant performance of the magnesium alloy is improved by adding rare earth elements and the Nb element into the magnesium alloy; and grains are refined by adding the Zr and M elements, so that the heat resistant magnesium alloy which has good mechanical properties, machinability, mobility and die-casting properties and is suitable for casting in particular to die-casting is obtained.