In various embodiments, three-dimensional layered metallic parts are substantially free of gaps between successive layers, are substantially free of cracks, and have densities no less than 97% of the theoretical density of the metallic material.

In various embodiments, wire composed at least partially of arc-melted refractory metal material is utilized to fabricate three-dimensional parts by additive manufacturing.

A heat-resistant and soluble magnesium alloy, and a preparation method having an elemental composition at the following atomic percentage: Lu 0.10% to 8.00%, Ce 0.001 to 0.05%, Al 0.10% to 0.60%, Ca 0.001% to 0.50%, Cu 0.01% to 1.00%, Ni 0.01% to 1.00%, impurity elements <0.30%, and the rest is Mg, and formed in magnesium alloys are high temperature phase of Lu.sub.5Mg.sub.24, Mg.sub.2Cu, Mg.sub.2Ni, Mg.sub.12Ce, Al.sub.11Ce.sub.3 and (Mg, Al).sub.2Ca, and Long Period Stacking Ordered (LPSO) phases as Mg—Lu—Al and Mg—Ce—Al. The magnesium alloy has good mechanical performances at 150° C., and a dissolution rate of 30 to 100 mg.Math.cm.sup.−2h−1 in a 3% KCl solution at 93° C.

An aluminum alloy fin material for a heat exchanger is made of an aluminum alloy including 0.05 mass % to 0.5 mass % of Si, 0.05 mass % to 0.7 mass % of Fe, 10 mass % to 2.0 mass % of Mn, 0.5 mass % to 1.5 mass % of Cu, and 3.0 mass % to 7.0 mass % of Zn, with the balance being Al and unavoidable impurities. In an L-ST plane thereof, second-phase grains having an equivalent circle diameter equal to or more than 0.030 μm and less than 0.50 μm have a perimeter density of 0.30 μm/μm.sup.2 or more, second-phase grains having an equivalent circle diameter equal to or more than 0.50 μm have a perimeter density of 0.030 μm/μm.sup.2 or more, and specific resistance thereof at 20° C. is 0.030 μΩm or more.

According to a casting method, a molten metal is sustained at a sustain position between a casting and the next casting, and the molten metal flow is divided from one pouring gate (44) to a plurality of sprue runners (46 and 47) in the casting. The sprue runners (46 and 47) are branched by a V-shaped portion (45) in a V-shape, and the sustain position of the molten metal is set above (any one of P1, P2 and P4) the V-shaped portion (45). The V-shaped portion (45) is filled with the molten metal while a repeated casting is carried out.

According to a casting method, a molten metal is sustained at a sustain position between a casting and the next casting, and the molten metal flow is divided from one pouring gate (44) to a plurality of sprue runners (46 and 47) in the casting. The sprue runners (46 and 47) are branched by a V-shaped portion (45) in a V-shape, and the sustain position of the molten metal is set above (any one of P1, P2 and P4) the V-shaped portion (45). The V-shaped portion (45) is filled with the molten metal while a repeated casting is carried out.

In various embodiments, three-dimensional layered metallic parts are substantially free of gaps between successive layers, are substantially free of cracks, and have densities no less than 97% of the theoretical density of the metallic material.

In various embodiments, three-dimensional layered metallic parts are substantially free of gaps between successive layers, are substantially free of cracks, and have densities no less than 97% of the theoretical density of the metallic material.

An NPR non-magnetic steel material for rock bolt and a production method thereof are disclosed. The NPR non-magnetic steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, MN: 15-20%, Cr: 1-18%, Si: 0.3-3%, Ca: 0.05-0.15%, Cu: ≤0.03%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR non-magnetic steel material for rock bolt and the production method thereof effectively solve the problems of steel materials for rock bolt in the prior art such as strong magnetism, low tensile strength and low effective elongation. The NPR non-magnetic steel material for rock bolt has a fully-austenitized structure and is non-magnetic, its yield strength is adjustable in the range of 600-1000 MPa, and its elongation is adjustable in the range of 20-60%.

The present disclosure provides a pulse current assisted uncanned rolling method for titanium-TiAl composite plates, including the following specific steps: 1. preparing titanium alloy sheets; 2. preparing TiAl alloy sheets; 3. uncanned lay-up; 4. pulse current assisted hot-rolling; 5. separation and subsequent processing, thus getting the titanium-TiAl composite plates. The composite plates are of good quality on the surface without oxide layer shedding, no cracks at the edges and the ends, with uniform and fine microstructures, good bonding interface and excellent mechanical properties.