diff --git a/src/MaterialManager.py b/src/MaterialManager.py
index bdfbaa2..7a221c7 100644
--- a/src/MaterialManager.py
+++ b/src/MaterialManager.py
@@ -19,10 +19,20 @@ def changeMaterial(self, material) -> bool:
                 self.carManager.setMaterial(materialType.Carbon)
                 returnText = "Material is changed to Carbon."
 
+            case _ metarialType.AlloyX:
+                self.carManager.setMaterial(materialType.AlloyX)
+                returnText = "Material is changed to AlloyX."
             case _:
-                returnText = "Material seletion is invalid."
+                returnText = "Material selectioın is invalid"
 
         return self._announceMaterial(returnText)
 
     def _announceMaterial(self, text: str) -> bool:
-        return self.announcer(text)
+        returnValue = False
+        try:
+            returnValue = self.announcer(text)
+        except:
+            print("Announcement of materials type is failed.")
+            returnValue = False
+        finally:
+        return returnValue
diff --git a/src/Util.py b/src/Util.py
index 81ab0ba..4383ce3 100644
--- a/src/Util.py
+++ b/src/Util.py
@@ -1,3 +1,3 @@
 from enum import Enum
 
-materialType = Enum('Titanium', 'Carbon')
+materialType = Enum('Titanium', 'Carbon','AlloyX')