Magnesium-Alloy Member, Compressor for Use in Air Conditioner, and Method for Manufacturing Magnesium-Alloy Member

Abstract

A magnesium alloy member capable of achieving a mechanical strength and a high-temperature fatigue strength sufficient for a compressor for in automotive air conditioners The magnesium alloy member is formed by subjecting a cast material of a magnesium alloy containing, on the basis of mass %, from 0.3% to 10% calcium (Ca), from 0.2% to 15% aluminum (Al), and from 0.05% to 1.5% manganese (Mn), and containing calcium (Ca) and aluminum (Al) at a calcium/aluminum mass ratio of from 0.6 to 1.7, with the balance being magnesium (Mg) and inevitable impurities to plastic working (extrusion processing) at from 250° C. to 500° C. This makes it possible to obtain a magnesium alloy member having a room-temperature 0.2% proof stress of 300 MPa or more and a 150° C. fatigue strength of 100 MPa or greater.

1 . A magnesium alloy member obtained by subjecting a cast material of a magnesium alloy containing, on the basis of mass %, from 0.3% to 10% calcium, from 0.2% to 15% aluminum, and from 0.05% to 1.5% manganese, and containing calcium and aluminum at a calcium/aluminum mass ratio of from 0.6 to 1.7, with the balance being magnesium and inevitable impurities to plastic working at from 250° C. to 500° C. 
     
     
         2 . The magnesium alloy member according to  claim 1 , wherein the plastic working is followed by solution heat treatment and artificial aging treatment. 
     
     
         3 . The magnesium alloy member according to  claim 2 , wherein after the plastic working, the magnesium alloy member is subjected to solution heat treatment to retain the magnesium alloy member for at least 0.08 hour at a treatment temperature of from 450° C. to 510° C., and then, the resulting member is subjected to artificial aging treatment to retain the resulting member for at least 0.3 hour at a treatment temperature of from 150° C. to 250° C. 
     
     
         4 . A magnesium alloy member obtained by subjecting a cast material of a magnesium alloy containing, on the basis of mass %, from 0.3% to 10% calcium, from 0.2% to 15% aluminum, and from 0.05% to 1.5% manganese, and containing calcium and aluminum at a calcium/aluminum mass ratio of from 0.6 to 1.7, with the balance being magnesium and inevitable impurities to plastic working; and having a room-temperature 0.2% proof stress of 300 MPa or greater and a 150° C. fatigue strength of 100 MPa or greater. 
     
     
         5 . The magnesium alloy member according to  claim 1 , wherein the plastic working is extrusion processing. 
     
     
         6 . A compressor for air conditioners using, as a mechanical part thereof, the magnesium alloy member as claimed in  claim 1 . 
     
     
         7 . A method for manufacturing a magnesium alloy member, comprising subjecting a cast material of a magnesium alloy containing, on the basis of mass %, from 0.3% to 10% calcium, from 0.2% to 15% aluminum, and from 0.05% to 1.5% manganese, and containing calcium and aluminum at a calcium/aluminum mass ratio of from 0.6 to 1.7, with the balance being magnesium and inevitable impurities to plastic working at from 250° C. to 500° C. 
     
     
         8 . The method for manufacturing a magnesium alloy member according to  claim 7 , wherein the plastic working is followed by solution heat treatment and artificial aging treatment. 
     
     
         9 . The method for manufacturing a magnesium alloy member according to  claim 8 , further comprising, after the plastic working, subjecting the magnesium alloy member to solution heat treatment to retain the member for at least 0.08 hour at a treatment temperature of from 450° C. to 510° C., and then, subjecting the resulting member to artificial aging treatment to retain the resulting member for at least 0.3 hour at a treatment temperature of from 150° C. to 250° C. 
     
     
         10 . The method for manufacturing a magnesium alloy member according to  claim 7 , wherein the plastic working is extrusion processing.