National Institute for Materials Science

Toyota Jidosha Kabushiki Kaisha

Kobe University

Hidetoshi Somekawa

Toshiji Mukai

Alok Singh

Yoshiaki Osawa

Akira Kato

Akiko Yamamoto

Tadanobu Inoue

Sachiko Hiromoto

Norio Maruyama

Tetsuya Shoji

Kazuhiro Hono

Kota Washio

Alok Shingh

Tomoyuki Honma

Adding multiple solute elements could create fracture origin through formation of intermetallic compound due to bonding of added elements. While maintaining microstructure for activating non-basal dislocation movement, additive elements not to create fracture origin, but to promote grain boundary sliding are preferably found from among inexpensive and versatile elements. Provided is Mg-based wrought alloy material including two or more among group consisting of Mn, Zr, Bi, and Sn; and Mg and unavoidable constituents, having excellent room-temperature ductility and characterized by having finer crystal grain size in Mg parent phase during room-temperature deformation and in that mean grain size in matrix thereof is 20 &#x3bc;m or smaller; rate of (&#x3c3;&#x2212;&#x3c3;)/&#x3c3;(maximum load stress (&#x3c3;), breaking stress (&#x3c3;)) in stress-strain curve obtained by tension-compression test of the wrought material is 0.2 or higher; and resistance against breakage shows 200 kJ or higher.

Magnesium-based wrought alloy material and manufacturing method therefor

Provided is Mg-based alloy wrought material having improved ductility, formality, and resistance against fracture. Intermetallic compounds may be formed by mutual bonding of added elements to be a fracture origin. While maintaining microstructure for activating non-basal dislocation movement of Mg-based alloy wrought material, added elements to create no fracture origin, but to promote grain boundary sliding were found from among inexpensive and versatile elements. Provided is Mg-based alloy wrought material including at least one element from Zr, Bi, and Sn and at least one element from Al, Zn, Ca, Li, Y, and Gd wherein remainder comprises Mg and unavoidable impurities; an average grain size in a parent phase is 20 &#x3bc;m or smaller; a value of (&#x3c3;&#x2212;&#x3c3;)/&#x3c3;(maximum load stress (&#x3c3;), breaking stress (&#x3c3;)) in a stress-strain curve obtained by tension-compression tests of the wrought material is 0.2 or higher; and resistance against breakage shows 100 kJ or higher.

Magnesium-based alloy wrought product and method for producing same

In order to improve the ductility or formability of a magnesium alloy, addition of rare earth elements or refinement of grain size is often used. However, conventional additional elements inhibit the action of grain boundary sliding for complementing plastic deformation. Therefore, it is required to search for additional elements that act to facilitate the grain boundary sliding not only at a conventional deformation speed but also in a higher speed range while maintaining a microstructure for activating non-basal dislocation. The present invention is to provide a wrought processed Mg-based alloy having excellent ductility at room temperature, which consists of 0.25 mass % or more to 9 mass % or less of Bi, and a balance of Mg and inevitable components, and is characterized by having an average grain size of an Mg parent phase after solution treatment and hot plastic working after casting of 20 &#x3bc;m or less.

Wrought processed magnesium-based alloy and method for producing same

Provided is an Mg alloy and a method for producing same able to demonstrate high strength without requiring an expensive rare earth element (RE). The high-strength Mg alloy containing Ca and Zn within a solid solubility limit and the remainder having a chemical composition comprising Mg and unavoidable impurities is characterized in comprising equiaxial crystal particles, there being a segregated area of Ca and Zn along the (c) axis of a Mg hexagonal lattice within the crystal particle, and having a structure in which the segregated area is lined up by Mgatomic spacing in the (a) axis of the Mg hexagonal lattice. The method for producing the high-strength Mg alloy is characterized in that Ca and Zn are added to Mg in a compounding amount corresponding to the above composition and, after homogenization heat treating an ingot formed by dissolution and casting, the above structure is formed by subjecting the ingot to hot processing.

High strength Mg alloy and method for producing same

The quasicrystal phase and/or quasicrystal-like phase particles, which is composed of the Mg&#x2014;Zn&#x2014;Al, are dispersed into Mg-base alloy material for strain working. The microstructure in this material does not include the dendrite structure, and the size of the magnesium matrix is 40 &#x3bc;m or less than 40 &#x3bc;m. The present invention shows that the quasicrystal phase and/or quasicrystal-like phase is able to form by addition of the Zn and Al elements except for the use of rare earth elements. In addition, the excellent trade-off-balancing between strength and ductility and reduction of the yield anisotropy, which are the serious issues for the wrought processed magnesium alloys, is able to obtain by the microstructure controls before the strain working process.

Mg-base alloy

A magnesium-based medical device which can adjust a degree of corrosion within a wide range of period such that the device can maintain a sufficient strength only during a desired period and disappears within a desired period thereafter and a manufacturing method thereof are provided. A magnesium-based medical device of the present invention is a magnesium-based medical device in which a base material is made of magnesium or a magnesium alloy, wherein a corrosion-resistant film is formed on a surface of the base material, and variation in surface hardness of the formed corrosion-resistant film in the in-plane direction is less than 21 in terms of a dispersion value of Vickers hardness.

Magnesium-based medical device and manufacturing method thereof

An object of the invention is to provide a magnesium alloy having high strength and sufficient formability. A magnesium alloy mainly contains magnesium and has high tensile strength and high compression strength. The crystal grain structure of the alloy has a high angle grain boundary, and the inside of the crystal grain surrounded by the high angle grain boundary is composed of subgrains.

Magnesium alloy

Provided is a Mg alloy, in which precipitated particles are dispersed and which has enhanced tensile strength regardless of the size of the magnesium matrix grains therein.

Mg alloy

An Mg alloy provided with high strength and high ductility by matching the strength and ductility in tensile deformation and compressive deformation at the same levels is provided. The Mg alloy of the present invention is characterized by having a chemical composition consisting of Y: 0.1 to 1.5 at % and a balance of Mg and unavoidable impurities and having a microstructure with high Y regions with Y concentrations higher than an average Y concentration distributed at nanometer order sizes and intervals. The present invention further provides an Mg alloy characterized by having a chemical composition consisting of Y: more than 0.1 at % and a valance of Mg and unavoidable impurities, having a microstructure with high Y regions with Y concentrations higher than an average Y concentration distributed at nanometer order sizes and intervals and having an average recrystallized grain size within the range satisfying the following formula 1:&#x2212;0.87+1.10&#x3c;log&#x3c;1.14+1.48,&#x2003;&#x2003;formula 1:where c: Y content (at %) andd: average recrystallized grain size (&#x3bc;m).

Mg alloy and method of production of same

An Mg-base alloy shows that an Mg-base alloy, which is added Zn and Al to magnesium, has a composition represented by (100-a-b) wt % Mg-a wt % Al-b wt % Zn, and satisfying 0.5&#x2266;b/a. The alloy can reduce yield anisotropy, which is a serious problem for the wrought magnesium alloy, while maintaining a high strength property. The alloy is produced by additive elements, such as Zn and Al, which are easily obtained in place of rare earth elements.

Mg-based alloy

As a novel biodegradable metallic material the degradation speed of which in vivo can be controlled over a broad scope while achieving desired mechanical properties such as strength, work hardening and ductility without restricting the shape of an implant device, it is intended to provide a magnesium-based biodegradable metallic material which comprises Mg containing Mg as the major composition and having a concentration of inevitable impurities equal to or less than 0.05 atomic %, is free from precipitates or intermetallic compounds, and has an average grain size being regulated to equal to or less than &#xbc; of the minimum part of the material.

Magnesium-based biodegradable metallic material

A magnesium alloy exhibiting high strength and high ductility, characterized in that it comprises 0.03 to 0.54 atomic % of certain solute atoms belonging to 2 Group, 3 Group or Lanthanoids of the Periodic Table and having an atomic radius larger than that of magnesium and the balanced amount of magnesium, and has a fine crystal grain structure wherein solute atoms having an average crystal grain diameter of 1.5 &#x3bc;m or less and being unevenly present in the vicinity of crystal grain boundaries at a concentration being 1.5 to 10 times that within crystal grains, wherein an atom selected from the group consisting of Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu can be used as the above solute atom; and a method for producing the magnesium alloy. The above magnesium alloy is novel and achieves high strength and high ductility at the same time.

Growing community of inventors

Ibaraki, Japan

Hidetoshi Somekawa