Improved castable magnesium alloy

Abstract

This invention relates to a magnesium alloy comprising: (a) 1.32-1.8 w1% Gd, (b) 2-3.6 w1% Nd, (c) 0.55-0.7 w1% Zr, (d) 0.20-0.40 w1% Zn, and (d) at least 85 wi % Mg, wherein the ratio of Gd:Nd (wt %) is 0.40-0.63. The invention also relates to an aircraft component comprising the magnesium alloy, as well as a to a method for producing the magnesium alloy.

1 . A magnesium alloy comprising:
 (a) 1.32-1.8 wt % Gd,   (b) 2-3.6 wt % Nd,   (c) 0.55-0.7 wt % Zr,   (d) 0.20-0.40 wt % Zn, and   (d) at least 85 wt % Mg,   wherein the ratio of Gd:Nd (wt %) is 0.40-0.63.   
     
     
         2 . A magnesium alloy as claimed in  claim 1 , having an Ultimate Tensile Strength, when sand cast into a 200 mm×200 mm×25.4 mm plate and subjected to a T6 ageing process, of at least 310 MPa as measured according to ASTM B557M-15. 
     
     
         3 . A magnesium alloy as claimed in  claim 2 , having an Ultimate Tensile Strength, when sand cast into a 200 mm×200 mm×25.4 mm plate and subjected to a T6 ageing process, of at least 315 MPa as measured according to ASTM B557M-15. 
     
     
         4 . A magnesium alloy as claimed in  claim 1 , wherein a ratio of Gd:Nd (wt %) is 0.40-0.61. 
     
     
         5 . A magnesium alloy as claimed in  claim 4 , wherein the ratio of Gd:Nd (wt %) is 0.40-0.57. 
     
     
         6 . A magnesium alloy as claimed in  claim 1 , wherein the alloy comprises 1.35-1.8 wt % Gd. 
     
     
         7 . A magnesium alloy as claimed in  claim 5 , wherein the alloy comprises 1.40-1.70 wt % Gd. 
     
     
         8 . A magnesium alloy as claimed in  claim 1 , wherein the alloy comprises 2.2-3.4 wt % Nd. 
     
     
         9 . A magnesium alloy as claimed in  claim 8 , wherein the alloy comprises 2.6-3.1 wt % Nd. 
     
     
         10 . A magnesium alloy as claimed in  claim 1 , wherein the alloy comprises 0.6-0.7 wt % Zr. 
     
     
         11 . A magnesium alloy as claimed in  claim 1 , wherein the alloy comprises at least 90 wt % Mg. 
     
     
         12 . A magnesium alloy as claimed in  claim 11 , wherein the alloy comprises at least 92 wt % Mg. 
     
     
         13 . A magnesium alloy as claimed in  claim 1 , wherein the alloy optionally comprises (i) up to 0.4 wt % of rare earth metals other than Gd and Nd, (ii) up to 0.05 wt % Ag, (iii) up to 0.01 wt % Cu, (iv) up to 0.010 wt % Fe, (v) up to 0.0020 wt % Ni, (vi) up to 0.01 wt % of any other elements, with the remainder being magnesium. 
     
     
         14 . A magnesium alloy as claimed in  claim 1 , wherein the alloy, when sand cast into a 200 mm×200 mm×25.4 mm plate and subjected to a T6 ageing process, has a mean planar grain size of 10-100 μm as measured according to ASTM E112-13. 
     
     
         15 . A magnesium alloy as claimed in  claim 14 , wherein the alloy, when sand cast into a 200 mm×200 mm×25.4 mm plate and subjected to a T6 ageing process, has a mean planar grain size of 20-80 μm as measured according to ASTM E112-13. 
     
     
         16 . A magnesium alloy as claimed in  claim 1 , wherein the alloy comprises a first crystal phase and a second crystal phase. 
     
     
         17 . A magnesium alloy as claimed in  claim 16 , wherein the alloy, when sand cast into a 200 mm×200 mm×25.4 mm plate and subjected to a T6 ageing process, comprises at least 98% of said first crystal phase. 
     
     
         18 . An aircraft component comprising a magnesium alloy as claimed in  claim 1 . 
     
     
         19 . An aircraft component as claimed in  claim 18 , wherein the aircraft component is a drive train component, an engine component or a structural component. 
     
     
         20 . An aircraft component as claimed in  claim 18 , wherein the aircraft component is an electric aircraft component. 
     
     
         21 . A method for producing a magnesium alloy as claimed in  claim 1 , the method comprising the steps of:
 (a) heating Mg, Gd, Nd, Zr and Zn to form a molten magnesium alloy comprising 1.32-1.8 wt % Gd, 2-3.6 wt % Nd, 0.55-0.7 wt % Zr, 0.20-0.40 wt % Zn and at least 85 wt % Mg, wherein the ratio of Gd:Nd (wt %) is 0.40-0.63,   (b) mixing the resulting molten magnesium alloy, and   (c) casting the magnesium alloy.