An electrically conductive GaAs crystal has an atomic concentration of Si more than 1×10.sup.17 cm.sup.−3, wherein density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm.sup.−2. In this case, it is preferable that the conductive GaAs crystal has a dislocation density of at most 2×10.sup.−2 cm.sup.2 or at least 1×10.sup.−3 cm.sup.2.

An electrically conductive GaAs crystal has an atomic concentration of Si more than 1×10.sup.17 cm.sup.−3, wherein density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm.sup.−2. In this case, it is preferable that the conductive GaAs crystal has a dislocation density of at most 2×10.sup.−2 cm.sup.2 or at least 1×10.sup.−3 cm.sup.2.

Spherical shaped ejection particles are ejected against a surface of a sintered body including hard particles and a binder metal phase bonding the hard particles together, with a compressed gas at an ejection pressure of from 0.2 MPa to 0.6 MPa or at an ejection velocity of from 80 m/s to 200 m/s and the spherical ejection particles having a hardness not less than the hardness of the binder metal phase and that is a hardness of 1000 HV or less and being particles having an average particle diameter from 20 μm to 149 μm. Thus, plastic deformation resulting from such impact and the instantaneous temperature rise and cooling occurring at the impact sites micronizes the structure of the binder metal phase, causes a change to a dense structure, and imparts compressive residual stress thereto. This results in strengthening, and enables prevention of brittle fracture in the sintered body.

Spherical shaped ejection particles are ejected against a surface of a sintered body including hard particles and a binder metal phase bonding the hard particles together, with a compressed gas at an ejection pressure of from 0.2 MPa to 0.6 MPa or at an ejection velocity of from 80 m/s to 200 m/s and the spherical ejection particles having a hardness not less than the hardness of the binder metal phase and that is a hardness of 1000 HV or less and being particles having an average particle diameter from 20 μm to 149 μm. Thus, plastic deformation resulting from such impact and the instantaneous temperature rise and cooling occurring at the impact sites micronizes the structure of the binder metal phase, causes a change to a dense structure, and imparts compressive residual stress thereto. This results in strengthening, and enables prevention of brittle fracture in the sintered body.

Disclosed are a BCC dual phase refractory superalloy with high phase stability and a manufacturing method therefor, the alloy comprising one or more of Ti, Zr, and Hf as Group 4 transition metals, one or more of Na and Ta as Group 5 transition metals, and Al, and having a structure of a BCC phase, wherein the BCC phase is composed of a disordered BCC phase and an ordered BCC phase, and wherein the ordered BCC phase is formed by allowing Al, which is a BCC phase forming element, to be soluted in an area of the BCC phase where the contents of the Group 5 transition metals are more than those of the Group 4 transition metals, so that the present disclosure provides a BCC dual phase refractory superalloy with high phase stability, characterized in that when a BCC dual phase with the ordered BCC phase and the disordered BCC phase separated from each other is formed by aging, the aging condition is precisely controlled through the apex temperature (T.sub.c) of the BCC phase miscibility gap, expressed by (Equation 1) below.

T.sub.c(K)=881.4+331.7*x+546.7*y+893.0*x*z (provided that, 0≤x≤1, 0≤y≤0.2, 0≤x+y≤1, and 0≤z≤1)  (Equation 1)

A light weight component, the light weight component including: a metallic foam core formed into a desired configuration; an external metallic shell applied to an exterior surface of the metallic foam core after it has been formed into the desired configuration; an inlet opening and an outlet opening formed in the external metallic shell in order to provide a fluid path through the metallic foam core; and a thermoplastic material injected into the metallic foam core via the inlet opening.

A light weight component, the light weight component including: a metallic foam core formed into a desired configuration; an external metallic shell applied to an exterior surface of the metallic foam core after it has been formed into the desired configuration; an inlet opening and an outlet opening formed in the external metallic shell in order to provide a fluid path through the metallic foam core; and a thermoplastic material injected into the metallic foam core via the inlet opening.

An electrically conductive GaAs crystal has an atomic concentration of Si more than 1×10.sup.17 cm.sup.−3, wherein density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm.sup.−2. In this case, it is preferable that the conductive GaAs crystal has a dislocation density of at most 2×10.sup.−2 cm.sup.2 or at least 1×10.sup.−3 cm.sup.2.

An electrically conductive GaAs crystal has an atomic concentration of Si more than 1×10.sup.17 cm.sup.−3, wherein density of precipitates having sizes of at least 30 nm contained in the crystal is at most 400 cm.sup.−2. In this case, it is preferable that the conductive GaAs crystal has a dislocation density of at most 2×10.sup.−2 cm.sup.2 or at least 1×10.sup.−3 cm.sup.2.

An electrical contact material (10) having: a conductive substrate (1) formed from copper or a copper alloy; a first intermediate layer (2) provided on the conductive substrate (1); a second intermediate layer (3) provided on the first intermediate layer (2); and an outermost layer (4) formed from tin or a tin alloy and provided on the second intermediate layer (3), wherein the first intermediate layer (2) is constructed as one layer of grains extending from the conductive substrate (1) side to the second intermediate layer (3) side, and wherein, in the first intermediate layer (2), the density of grain boundaries (5b) extending in a direction in which the angle formed by the grain boundary in interest and the interface between the conductive substrate and the first intermediate layer is 45° or greater, is 4 μm/μm.sup.2 or less; a method of producing the same; and a terminal.