A valve seat insert made of an iron-base sintered alloy is configured to have a structure in which the base matrix phase is a fine carbide precipitation phase in which a fine carbide being 10 m or less in size is precipitated and which has a hardness of 550 HV or more in Vickers hardness; and in the base matrix phase, hard-particles having a hardness of 650-1200 HV in Vickers hardness are dispersed in an area percentage of 20-40%, a diffusional phase is formed in an area percentage of more than 0% and not more than 5%, and solid-lubricant particles are dispersed in an area percentage of 0-5%. Even if a valve having a high face hardness of 400 HV or more, or 600 HV or more is used, a facing valve seat insert wears only slightly, improving valve train durability.

A valve seat insert made of an iron-base sintered alloy is configured to have a structure in which the base matrix phase is a fine carbide precipitation phase in which a fine carbide being 10 m or less in size is precipitated and which has a hardness of 550 HV or more in Vickers hardness; and in the base matrix phase, hard-particles having a hardness of 650-1200 HV in Vickers hardness are dispersed in an area percentage of 20-40%, a diffusional phase is formed in an area percentage of more than 0% and not more than 5%, and solid-lubricant particles are dispersed in an area percentage of 0-5%. Even if a valve having a high face hardness of 400 HV or more, or 600 HV or more is used, a facing valve seat insert wears only slightly, improving valve train durability.

A method for manufacturing a poppet valve or mushroom valve includes providing a mixture of metal powder and a binder, filling and pressing said mixture in a mold, to obtain a green product, removing the binder from the green product, and thermally sintering the green product to a poppet valve blank, by hot isostatic pressing. A poppet valve is also provided that is manufactured with this method.

A method for manufacturing a poppet valve or mushroom valve includes providing a mixture of metal powder and a binder, filling and pressing said mixture in a mold, to obtain a green product, removing the binder from the green product, and thermally sintering the green product to a poppet valve blank, by hot isostatic pressing. A poppet valve is also provided that is manufactured with this method.

A method of producing a finished essentially 100% dense homogenous alloyed metallic product. First, a metal powder is provided comprised of particles with each particle having a predetermined alloy content. Next, the metal powder is blended with a mixture of a lubricant and a binder to form a composite powder. That composite powder is then compacted in a compacting die at room temperature to form a green part. The lubricant and binder are then removed by heating the green part to at least a first temperature profile in a confined atmosphere with a predetermined dew point profile. Next, the remaining green part is heated to a second temperature higher than the first temperature and with predetermined dew point and H.sub.2/H.sub.2O ratio in a furnace atmosphere to remove surface oxides from the part. Finally, the part is densified into a finished or near net shape homogenous alloyed product.

An L10-FeNi magnetic powder has an average particle size of 50 nm to 1 m, and an average value of sphericity P of 0.9 or more. The sphericity P is defined as P=Ls/Lr, where Lr is a perimeter of an L10-FeNi magnetic powder particle on an image of a microscope, and Ls is a perimeter of a perfect circle that has a same area as the L10-FeNi magnetic powder particle on the image for which Lr is calculated.

An L10-FeNi magnetic powder has an average particle size of 50 nm to 1 m, and an average value of sphericity P of 0.9 or more. The sphericity P is defined as P=Ls/Lr, where Lr is a perimeter of an L10-FeNi magnetic powder particle on an image of a microscope, and Ls is a perimeter of a perfect circle that has a same area as the L10-FeNi magnetic powder particle on the image for which Lr is calculated.

Disclosed herein is a method and apparatus for forming pellets in a non-ambient environment such as a strong magnetic field. The apparatus includes a die body, a die bottom, a short push pin, a long push pin, a press tube, and an extended push pin. A powder is loaded into the die body, which is then positioned in the non-ambient environment, and the powder allowed to equilibrate. A pellet is then formed by pressing on the extended push pin while the powder is in the non-ambient environment.

The present invention relates to a method for manufacturing a sintered bearing having a bearing surface that forms a bearing gap with a shaft to be supported, in its inner periphery. This manufacturing method includes: a compacting step P2 of compacting a base powder containing a diffusion alloyed powder 11 prepared by partially diffusing a copper powder in an iron powder as a main material, a low-melting-point metal powder 14, and a solid lubricant to obtain a green compact, and a sintering step P3 of sintering the green compact 4 to obtain a sintered compact 4.

The present invention relates to a method for manufacturing a sintered bearing having a bearing surface that forms a bearing gap with a shaft to be supported, in its inner periphery. This manufacturing method includes: a compacting step P2 of compacting a base powder containing a diffusion alloyed powder 11 prepared by partially diffusing a copper powder in an iron powder as a main material, a low-melting-point metal powder 14, and a solid lubricant to obtain a green compact, and a sintering step P3 of sintering the green compact 4 to obtain a sintered compact 4.