1. A stent of biodegradable magnesium alloy, which contains the following components calculated on the total mass of the alloy: 5.0% of the mass. - 25.5% of the mass. dysprosium； 0.01% of the mass. - 5.0% of the mass. neodymium and / or europium； 0.1% of the mass. - 3.0% of the mass. zinc； 0.1% of the mass. - 2.0% of the mass. zirconium； balance up to 100.0% of the mass. magnesium, where the stent has a polymer coating. 2. The stent according to claim 1, where the alloy contains: 0.1% of the mass. - 2.0% of the mass. zinc. 3. The stent according to claim 1, where the alloy contains: 0.1% of the mass. - 0.3% of the mass. zirconium. 4. A stent according to any one of claims 1 to 3, wherein the alloy contains impurities. The stent according to any one of claims 1 to 3, where the alloy further comprises: 1 ppm - 0.3% of the mass. impurities, such as, for example, other metals, metal salts and non-metals. 6. A stent according to any one of claims 1 to 3, wherein the alloy does not contain yttrium and does not contain gadolinium. 7. The stent according to any one of claims 1 to 3, where the alloy contains in General no more than 0.1% of the mass. elements of terbium, holmium, erbium, thulium, ytterbium, and lutetium. 8. The stent according to claim 1, where the alloy consists of: 80.7% of the mass. - 94.7% of the mass. magnesium； 5.0% of the mass. - 15.0% of the mass. dysprosium； 0.1% of the mass. - 2.0% of the mass. neodymium； 0.1% of the mass. - 2.0% of the mass. zinc； 0.1% of the mass. - 0.3% of the mass. impurities, such as, for example, other metals, metal salts and non-metals； and, where the alloy does not contain yttrium and does not contain gadolinium. 9. The stent according to claim 1, where the alloy consists of: 82.4% of the mass. - 94.7% of the mass. magnesium； 5.0% of the mass. - 15.0% of the mass. dysprosium； 0.1% of the mass. - 2.0% of the mass. neodymium； 0.1% of the mass. - 0.3% of the mass. zirconium； 0.1% of the mass. - 0.3% of the mass. other metals, m
